I have a lot to say about this one!
Personally, one of us takes our invited child, the other does something else with our other child. When either me or my DH has been on our own with both, we ask the host in advance, making it clear we understand if it’s a no to bring the other and pay, we also offer to just drop off our invited child. The problem here is even though my eldest is in Year 1, nobody will drop and go. I would be very happy to host a drop and go or leave mine, but nobody will.
Here it seems to be the norm that parents pay sibling entry if it’s at soft play but they join in with the food (I don’t mind that as there is always far too much food). I did find it rude 2 parents didn’t let me know they were bringing a sibling though.
Funnily enough, my DD has just had her first party with an entertainer (limit 20) in a hall. She made it very clear she explicitly wanted siblings invited, as she knows a lot as they are her older brother’s friends. I went with this, and also as they are only 3 I did prefer parents to stay, so thought fair enough as they may have nobody to look after the other child. 2 single Mums did let me know in advance, they were so polite and really checked if I minded, explained their situation. Actually, 1 who came with all 4 children was amazing, her elder ones were a huge help with the younger ones and she offered to help me clear up after, they were a pleasure to host. For me it’s all about the communication in advance, not just turning up with extra guests.
So there were 16 children at DD’s party, but it did make me wonder when she makes more friends as she gets older how this will be with entertainer limits. It ultimately should be about the child who’s birthday it us surely- would they like siblings as part of the total guest number or not? I feel that’s got lost a bit. My parties as a child were just for my actual friends in my class.
My son’s soft play party cost £250 for 12, it would have been another £100 if I’d had to pay for siblings on the day, so it is unreasonable to expect the host to do that. I would never expect another parent to do that. One actually offered to have cover my DD recently (son’s best friend), as someone couldn’t make it, I wasn’t even planning on taking her so it was a lovely gesture and bonus, but absolutely not expected.
Some parents here have found the sibling/total number issue so awkward that they have opted out of doing parties altogether, which is a shame.