This does seem rather silly but DH said I should have said something and now I am thinking about how I would deal with it again.
It is a bit of a long story but hear goes...
On Saturday morning we go to swimming lessons at 8am. (nightmare I know!) Anyway DC2 and DC3 get in the pool and I watch with DC1. Initially I left my stuff (coats, shoes, DC1's clothes and towels etc) on the table and on the chairs in the viewing/café area whilst I got DC2 and 3 changed and DC1 had his lesson. However a couple of parents always moved my stuff or just sat around my stuff meaning I had to grab it back from around and under them. After a couple of weeks I decided we would sit on a different table without a view of the pool and leave my stuff on one chair. However they decided that instead of getting a chair from the rest of the café they would take all my stuff off the chair and dump it on the table.
A couple of weeks went by when DH came with me or they were not there and no more issues.
However this week we changed lessons so my DC go half an hour later - at the same time as there DC. Well DC1 and I were sat at one end of the table and these parents came and sat at the other end of the table. Then I got up and walked round the (very small) table to get a pencil for DC1 and when I returned one of the parents DC was sat on the chair I had been sat on. I literally had been 30 seconds. If it had been my DC I would have told them not to sit on a chair someone was obviously still using and to move as soon as that person came back. They just were oblivious to their child sat on the chair next the DC1 and me standing there without anywhere to sit and carried on talking.
I can't work out whether these parents are ignorant, rude or have some kind of vendetta against me.
So the next week if the same thing happens again or a similar thing happens what would you do - politely ask the parents to tell their child to move or stand around waiting.