HI Lynn,sharing my sons experience with you. When my son was on methylphenidate and abilify it gave us a good result,even in vacation he was extremely well managed with only abilify and without stimulant even for 21 days in stretch.Then as he is 6 years only ,i was little scared to give him both the medicines so i stopped abilify in tapering dose.FOR initial 3 weeks it was extreme aggression,violence and adamancy to do or not to do certain things just because he wants it was there,Even my husband suggested to restart abilify but i decided to wait, 3 weeks it was hell for a family.BUT after that i noticed these 2 major changes,
1)when he was on abilify plus stimulant there was irritability ,it has been reduced.Earlier i thought it comes naturally when stimulants are at the pick of action and he is expressive now.
2)his compulsive window shopping on portals then changing his mind, then again window shopping on portals has remarkably decreased.
now he is on only methylphenidate only but the same dose which was sufficient for him with abilify wass too low .HE needed increased dose with which he can thrive the whole day,so that dose we are trying nowadays.And other thing when he was on abilify in night, we were totally relaxed for the next day.but now we have to be very careful because when stimulant is wearing off his typical adhd behavior starts,before that other dose is required even in mild form.So it is all trial n error with lot of observation but it will help the child.
AND it all depends on child to child,how old is your grandchild?Other parents having experience of abilify and stimulant might have something different to say.I think first see independently which stimulant works for him then slowly add medicine for mood disorder.Good luck.