J.T.
if it was a "closed door party", I'd probably just decline, b/c I'd assume if they wanted siblings, it would be noted on the invitation... however, it's in a public place that is open for regular business. I'd take my 4 year old to the party, keep a loose eye on him, and the 3 year old and I would eat/play nearby on my dime, but separate from the party. if the party parent INVITED my 3 year old to have cake and such, and she had been behaving well, etc. - I'd allow it. and I can't believe a parent below TELLS a party host that she is bringing another child - tacky tacky tacky! i wouldn't even ASK if my additional child(ren) could join in the actual party if i paid, and i certainly wouldn't demand it! some parties have an actual head count limit, regardless of money, what a pickle you could put someone in, in addition to being just totally rude and selfish. even with twins, life's not about "equal", and it's never too early to teach that.