If I had not experienced it, I wouldn't understand it either.
First let me tell you what is worse than uninvited siblings. My daughter turned 6 years old, and we invited the entire kindergarten class since we were new to the area. Ten children rsvp'd.
That Saturday, only 5 of those children showed up at IPEZ. The moms brought siblings. Since I paid for 10 kids, I thought -- great, at least it wasn't wasteful.
The parents who rsvp & then don't show up irk me more than those who bring siblings. Then there are those parents who don't even rsvp.
Every time my now 7 yr. old is invited to a party, I'm in a quandry. I have a 5 yr. old daughter & they are very close.......one is in kindergarten/one in first grade. But I was like you - no they need to understand -- separate friends -- separate parties.
However, each time I took one to a party & talked to the host -- every single mom says -- why didn't you ask? it would have been fine to bring along your other daughter.
At home, I've left a sad little girl whose father is babysitting our 3 year old, and the hostess said it was absolutely fine.
Any parent would GLADLY pay for the other sibling. The emotional ramifications are worth it -- 10 bucks -- even 20 -- getting off easy compared to the moping, crying & jealousy it all creates.
Of course, my friend had a party at the Monkey Joe's in Apopka & invited the entire preschool class & then said, bring all your siblings. Well, some moms even brought neighbor kids. That was a little bit out of control. I think she ended up with 10 kids from the actual preschool class and 25 kids siblings & such -- maybe more.
Basically, it is a sticky situation all around. Normally, I had a rule, I would NEVER ask to bring any sibling to a birthday party.
Then, just recently, a NEW mommy friend was having a house party for her 2 yr. old & talking about the family & friends going. WEll, I asked if my husband & other children should come too? I wasn't sure the exact invitation; i mean, it was a house party (i always thought the more, the merrier at house parties).
I thought I was receiving some strange vibes about asking. What is the exact protocal? I'm glad I did ask because everyone had their spouse & children. I was a new friend, but what a fun day everyone had. She had a bouncy castle & a huge backyard play area. My new friend said she was new about all this sibling party stuff -- and she thought my 7 & 6 year old would be bored or not fit in (the birthday party was for her 2 year old son).
Essentially, now my new rule is that if I am giving a party, and the mom asks to bring along a sibling and offers to pay, I say "sure" (if it is at a special place).
If it is a house party, I say the more the merrier.
My sister-in-law doesn't have much help with my brother watching the kids. So she always WANTS to pay to bring along her other two sons -- or else her son cannot attend the party. It is difficult enough to find a babysitter for doctor's appts. -- let alone a babysitter for a birthday party.
Money doesn't grow on trees. If a parent asks to bring along another sibling & you mention they charge per head, and they offer to pay for the siblings -- then don't think twice about it.
Honestly, I still cringe when I receive an invitation for just one of my children -- but especially my girls who are so close in age. Your children are far apart in age & mine are close together (7,5,3). With my youngest, it is easier -- I tell the girls it is a baby party, so they aren't interested. But with my girls, just one grade apart, now I call & offer to pay if it is at some place.
If you haven't experienced it, you wouldn't understand really. It isn't about spoiling the kids -- but to a kid, a party is magical & everyone wants to have fun. When they are close in age, it is very, very difficult -- and really not worth the hassle to take one & not the other -- just go & do a family day than have the conflict.
It is like explaining to a childless couple who are having a big barbecue bash where they are having family member's children, but your kids -- you have to get a babysitter. It doesn't make sense when it is your own, so you just don't go.
Hope I shed some light. It is an awkward situation all the way around.
P.S. if you can imagine i have anything to add to my book here. it is just a short time frame that kids (and moms) will go through this. eventually as they become a little older, they do find their own friends......it is just at this tough age of preschool & young elementary school.