Anonymous wrote:My sibling's children went through a sort of phase at age 3 or 4 where our mom (their grandma) was their favorite person in the world

She's a wonderful grandma and helped care for them and doted on them, so why not.
This is a healthy approach.
If your child were in daycare you'd hear your child call you Miss DaycareTeacher and that would break your heart.
My kids are 7 &9 and call me by the name of their teacher once in a while.
Kids also do the preferred parent thing at this age, and it ebbs and flows. Try to look at it as a developmental stage, not a choice.