need advice on Bday party combo ( older & younger sibling)

we're having a combined bday party for 2 of my kids. (turning 7, and turning 3).

what do I do for the invites ?

I feel awkward putting both, because I dont want friends of one to feel they have to buy gifts for the other also ?
but someone told me it would be strange to make invites as if it were just one, and people come and see both and feel awkward ?

would you think it was strange if you got an invite for a friend, and then saw that it was the older/younger sibling's also ?

thanks for any feedback.

Re: need advice on Bday party combo ( older & younger sibling)

I don't know, but I was thinking of combining my kid's birthdays one day so I would love some feedback as well.