I did this for my first couple of years as a nanny and it worked well at the time. A friend of mine was nannying for a family who had a friend who was looking for someone PT and I decided to go with a recommended family and fill in the rest of my time with a second family since I really clicked with the first family. It was a great experience as I really enjoyed working with both families, but that being said, my more recent job searches have focused on FT positions. Even when I was working for two families who were friends, I always had any schedule changes/requests be done through me and while the families always knew "the other mother's" name, I did not give them each other's contact info. Pros and cons may vary for you, but here were mine:
PRO:
- parents spend more time with their kid(s) and are more active in their life/lives (I find these parents tend to be easier to talk to about their children and admit that this is also part value judgment by me - I've worked for parents with more and less direct involvement in the live(s) of their child(ren) and while I am not saying there is a right or wrong, I am saying that I prefer to work with more involved parents.)
- parents tend to have more flexibility in scheduling
- more variety with days/activities, particularly if ages of children are different
- less of a routine
CONS
- vacation time can be difficult to coordinate
- nanny must be on top of schedule and set down boundaries early, as nanny's non-work obligations can easily come third/fourth/fifth
- if working for more than one family in a day, there is an additional commute, possibly with "dead" time to make sure not late for second family
- less likely to be offered benefits, guaranteed or position to be paid legally (obviously need to ask as not impossible, my experience has been that those are more common traits of FT positions)
- less of a routine
OTHER SUGGESTIONS:
- do not work for more than one family in a day, as MB1/DB1 running late will make you late for MB2/DB2 (or you will spend a lot of time waiting to go into work)
- try to coordinate agreements, so you have similar amounts of PTO
- I think it's okay to have different rates with the different families as their situations are different. I would not discuss the specifics of this between families if it happens. I would discuss sick kid/PTO expectations.
- figure out your evening/weekend policy (I always did first come, first serve for non-scheduled hours.)
- If possible, try to get families to commit to a full days (or as long of days as you want to work) on a set schedule. Decide early on if you are interested in coordinating "trading" of time between families. (I recommend doing so only minimally and with notice. Make it clear that each family has absolute priority on their time.)