Sorry to come back, but I just had to see what everyone else had to say :) I'm still just shaking my head over here. Yeah. Dressing a baby as an elephant for a wedding? That is NOT an "Indian thing" :) Indian culture often has elephants used as symbols and decorations, but there is absolutely nothing where there must be an elephant present for a wedding to be legit, and there definitely isn't a thing where a baby must be dressed as an elephant. LOL :)
p.s. In addition to being Indian, and having lived in India on and off all my life - I also have a PhD in religious studies/anthropology of South Asia. If you need a "source" to quote to your in-laws, happy for you to use me.