Definitely put your foot down: "Mom, I am so glad you are joining us, but I have the trip set up in a certain way to spend the most time with my grandmother and follow DD's schedule. I am not comfortable spending every spare moment seeing other relatives. I would like to organize one or two gatherings where as many can join us as possible, and of course you can spend more of your time there if you wish. I am going with my original plan to rent a place in x neighborhood rather than stay at the apartment. I appreciate your understanding here."

I would balance the pros and cons of being in an un-walkable location with a kitchen compared to being in a hotel but having to eat many of your meals at restaurants.

Thanks everyone for the responses!

GGM has good days and not so good days, but for the most part is still pretty much independent and lives alone in her apartment that she's had since my father was a child. We have already decided not to stay with her so that we don't make it hard for her since having family over for a few hours at a time is way easier than housing them. Hence the plan to rent an apartment or something like that. We will most likely come every day or every other day for a few hours and a meal and then spend the rest of the time on our own in the city. Because we will have so much "free time" my mother is taking this as an opportunity to see just about everyone else.

I am considering the one-time here-is-DD-come-see-her event, and that way I have given opportunity and maybe everyone will be happy. I am even open to doing this at some great aunt's house somewhere. Transportation is going to be super fun since this would mean I now have to bring a car seat, wheras before we would have travelled by public transport from the airport to a very walkable city, an easy thing to do and I've done several times so I know what to expect. GGM lives 20 minutes walk from the touristy areas, if you walk slowly. I might buy a cheaper car seat and then just leave it behind when we come home.

I know about the travel papers for travelling without DH, so we are covered there. Hopefully he can come but if not, no problem.

The latest news is that somehow, my parents still own the apartment they had before we all emigrated. The current tenant has said he will be moving out so now my mother says we should just stay at this apartment... that I have never seen (other than when I was an infant) and I have no idea if it has any furniture or anything else. I'm putting my foot down on the hotel/apartment rental idea. It seems that just when thigns are starting to look calm again, here comes a new brilliant idea.

I visited my grandmother with my 10 month old son overseas when she was on her death bed.
The first day she was so excited to see him. But the second day she was very tired and asked my husband to take him outside because it was too overwhelming for her. I got to spend some one-on-one time with my grandmother.

I would plan to bring your DD with you to visit your grandmother, but not for every visit. Can your DD stay with your mother for a couple of your visits to GGM?

If you are traveling without your spouse, he will have to fill out some paperwork allowing you to take your daughter overseas without him.

seconding the idea of your mom taking your kid around for a couple hours so that you can relax or spend one-on-one time with your grandma. Also, when she sees how tough it is to wrangle an overtired/hungry/jetlagged toddler, she may be more willing to stick to events and timing that better suit your little one's needs.

Tell your mom you need a 2-week break from her planning talk.

It sounds like your mom is just getting over-excited. Just try to gently rein her in, and protect sleep and nap and regular meals at all costs. You can't expect her to not want to show off her grandchild to far distant family, and not to get all hyper about it. It's just the way it is. Pick a few key boundaries and stick to them, but don't sweat every little idea that pops out of her head.

Honestly, OP, this will be a really tiring trip for you no matter what. It is a huge undertaking and I sympathize. You sound like a really nice person who cares about family and the elderly. There are some good tips on this thread, but I will tell you this: I have never, ever regretted going above and beyond to make an older person happy. And the things I could have done for my grandmother but didn't do, I regret to this day.

Go on the visits you want to...don't go on the ones you don't. Let your mom take DD on a couple you do not want to be bothered with. I am sure you will like at least a few hours alone time during the trip.

No. You get there and then announce to the family "picnic on Thursday in Sherwood forest playground at 2pm! Can't wait to see everyone who can make it!"

You do not haul a toddler from house to house. Make everyone meet in one central location.

I see both sides. I understand you intended to make this trip solely about your GGM. I can understand that for your mother this is a big exciting trip because she is not considering the caring of a toddler and the strain that takes when traveling. It would seem a little silly to go all the way to another country with family and not visit them if you are visiting other family members.
I would try to have the trip extend to 2 weeks so you can have more down time to adjust and it won't feel so overwhelming if it is just a week and your mom wants to schedule a million activities and visits.
If you get a larger place with your mom can some of the family members come to visit you?
I think you can be a little selfish in requesting restaurants for family to meet at that are convenient to you or times that work best for your toddler because it is difficult to travel with a toddler. Maybe suggest a nearby park for them to come visit so DD gets playtime and then can still visit.
I would try to think of it as a great time to experience this trip with four generations of family which you may never experience again. Try to build in some down time and agree to some of the family visits for your mom's sake.
Also, your mom might settle down when she arrives and jet lag or she realizes that your toddler has jet lag or sees the pace your toddler needs to travel at with naps, breaks for food and snacks, etc.

Yes, I know, woe is me, life is so hard, etc etc. I am aware how this sounds.

I made a promise to my last surviving grandparent that I will take my DD, who will be about 18 months old, to visit for 1-2 weeks this summer. (So, great-grandmother to my daughter, lets call her GGM.) GGM is my father's mother, and my father was an only child, so DD is her only great-grandchild. GGM is in declining health and my relationship with her has always been pretty good considering she lives in Europe and I was raised here. I am pretty excited to have the opportunity to go visit, especially since I haven't been in about 3 years. DH doesn't know if he will be able to join us, and it would be unlikely he could get away from work for that long, but this is expected. No problems there.

My mother has decided that she is joining us. It is her native country, and we have a lot of extended family there, and she is super excited to go. I did not ask her, she just kind of invited herself along and at the time I thought, hey, an extra pair of hands to help with DD, great! So I didn't say anything.

Now, every conversation I have with her revolves around who we are going to see, what we are going to do, where we are going to eat, and so on. Basically, I planned on getting a hotel or an apartment for a week and spending a lot of time with GGM, but now we have to visit all the extended family on both sides of the family and basically show off how cute DD is. My mother is now even looking into hotels in a busy part of town near cafes and tourist spots, and about a 20 min walk from GGM, and is talking about what clothes DD should have and what things we need to bring.

This is getting crazy. I have told her to get her own place to stay but her argument that we can save a lot of money if we get a 2 bedroom place is a good one. I have told her I have no interest in seeing anyone but GGM but she acts like she doesn't remember me saying that every time it comes up. I have even tried to say that DH hasn't figured out if he can come yet, but she says the 2 bedroom idea is still a great one.

Her arguments are mostly valid. The family will want to see DD, the housing situation would be cost-effective, and she can probably be helpful when it comes to DD in a foreign country. I have been several times but she grew up there so obviously she knows it better. I am just over the constant planning that seems to schedule every single minute of the trip. She has no off button.

I guess I don't know why I'm writing here but maybe someone has been through this with a good outcome and hasn't lost their mind and can tell me that running around to people's houses with a toddler in tow is actually a perfectly reasonable idea.