Read again. The children do not lift the balls. They push the already lifted balls down a slope while their mothers stand beside them.
Four kids are not too many for me to handle, except that I can’t fit them in my car. Children under 4 years or 40 pounds are in a full car seat and children under 8 are in booster seats. Children under 12 cannot sit in the front seat. I can fit TWO seats in my car. That presents a fairly large problem with your idea, in my opinion. Also, I don’t know any mother, including myself, who would let their 4 y/o go on an outing like that. I don’t even let my mother in law drive my child around.
I am not asking parents for additional supervision. Parents of 4 year olds just do it. They do not drop their children off at a party. They stay there. They will naturally watch their child because that is what parents do. Everyone just pitches in and keeps the kids from going completely bonkers. The parents with younger kids tend to take over keeping an eye on the little ones and those without gravitate toward watching the older ones. I have been to enough parties to know this is normal. When my daughter is invited to a party I don’t shove her off onto the host and say, “Well, you invited her, you deal with her.” That just isn’t what you do with kids this age.
Entertaining the younger kids is a good idea. A nearby lane is probably a good solution and, based on the day and time, there should be plenty of room to run around without bothering other patrons. The arcade is also right there and children that age love to just push the buttons and watch the lights. Keeping them entertained is not the issue. Actually, neither is their ability to lift the ball or parental involvement. Paying for them if their parents want them to bowl along with their invited sibling is the issue I asked for advice on.
Besides, what makes you think this is some huge event? I’m talking 10-ish kids plus some younger siblings. This has been done quite successfully in our group many times, but never as a party – only as a get-together where everyone paid their own way. That is why I am asking about who pays for younger siblings and, honestly, not much else. I’ve got the rest down, thanks.