4 year olds party in the park

[SassySpain]

OK, nothing too stressful since I'm 8 months pregnant and DH is nervous... no music possibilities and not too much paraphernalia due to transport difficulties... so what do we do? Also nothing too wordy or song based because it has to be done easily in Spanish since the majority will be non-english kids (we live in Spain). Should be lots of adults because parents will be staying so I could enlist help from them for some things. Any ideas? Especially non-competitive ones or ones where one kid is not put on the spot too much.
Thanks, Sx

DS1 went to a party in the park where they got a train to the place whre the park was, each had a parent/other grown up and each brought their own picnic. Party persons mum supplied little cakes and was going to do pass the parcel after they had eaten but it got left onm the bench after a (very minor) incident

treasure hunt to find little sweets?

what about a mini football game or 3 legged race?