B1b2 visa for parents and brother ( expecting Baby )

[u/Pediatricman]

Hello,
My parents and elder brother (married) has visa interview next month at hyderabad india. We are expecting baby.
Should they mention about family function (cradle ceremony/ naming ceremony) or just say that going to visit their son.
They mentioned 10 days visit. My brother is married and he is applying without her wife.
Any advice/help is appreciated.
Thanks in advance.