Advice on Multivitamin/Abidec

What Multivitamins do your little ones take? Also, do you give multivitamins twice a day? My daughter hasn’t been eaten well since having her final immunisation and my MIL suggested giving her Multivitamins twice a day even though it says only once 😕 she thinks it will regain my daughters appetite and I’m not convinced lol I’ve asked my mum and she is also as confused as me 😂 I just wanted to know if this was a common thing? I haven’t done it because I don’t think it is necessary, I’m just curious.