How do I word my invitations?

[scrappydappydoo]

I'm doing all the invites for DDs party. We're having a church hall thing for approx 30 kids (joint party for dd1 and dd2). I want to put on the invite that I expect parents to stay cos it will be bit mad and all children are pre-school (its dd1s 4th and dd2s 2nd). How can word this on the invite so it sounds friendly rather than demanding or too vague.
I've been to a couple of similar parties where parents have dropped their 3 yr olds off and left. I just don't want that responsibility at this age!

Include all names on the invitation?

Add a line specifying: at least one parent per two children? Why not be blunt?

My DD is 4 this year and, so far, she's never been to a party where I was expected to leave, nor has anyone dropped off their children and legged it! Perhaps word the invitation (depending on the time of the party) to include "sandwiches and tea/coffee for parents".
Or, speak to the parents you know well enough and say you're worried about managing all the children and could they please stay? That way should you end up with a reasonable adult/child ratio.

I've seen plenty dump and run at a 4yo's party. Agree with WingedVictory's wording.

We've received invitations addressed as follows: Dear X and one of your parents, I'd like you both to come to my Xth birthday party....

The alternative is to include a sentence somewhere at the bottom saying: We are expecting a parent to accompany and stay with their child for the duration of the party. If this is not possible please let me know when you RSVP. Thank you!

Beware that requiring a parent may mean additional siblings appear too....

dear X you and a parent are invited..
or
you are invited to celebrate X s birthday, cake and squash for kids, tea/ coffee and cake for parents.
or
you are invited to a family party...

I think 30 parents hanging around a party would be a pain in the neck. I think the 2 year olds' parents will stay anyway and you could ask a few parents of the 4 year olds beforehand if they can stay and help out.