If having more than one food seems to be the issue, I would give one food at a time and hold off on the drink till the end (obviously if they're actually thirsty before then, you give them something to drink but the drink sits by you). I'd also make sure we were all ready to sit down and eat before I called them to the table so you can be right there to stop things before they start (easier said than done, I know!).
My daughter used to want to either fill up on drink or eat all the starch first (and then lose interest in veg and meat, if we have it) so I started giving her veg to start and after she's had a few bites, a little bit of whatever meat we might have, and after she's tried a bit of that, the starch where she will usually fill up. I would also hold off on giving her a drink till she had eaten. I didn't announce that since she was going to fill up on rice and water, I was going to keep those till later, I just filled her plate a little at a time while we were talking and having dinner. It seemed to work. It's just been a little while and now she's pretty much outgrown her the problems and she gets all her food at one time.
Also, playing with food means she's done, period. And if they're bored enough to start playing with food before they're finished, maybe you could just try teeny portions. It was really hard for me to "get" just how little food a two or three year old actually needs. If we were having two or three different things, a tablespoon of each might be all she'd eat and she was probably three before she could eat a whole (medium) banana. Sometimes she still can't finish it. Even now I give her half at a time just in case she can't eat it all. I don't tell her I'm keeping half, I just give her half and if she asks for the rest, I give her that when she finishes the first part. It sounds kind of controlling and micro managing, but I just do it while going on with our normal meals and convo and she doesn't seem to notice - or she does notice but she doesn't care.
I guess these are all just examples of how to give them what they need without giving them enough for them to waste. It's one thing if *I* over fill her plate and she can't finish or if she just misjudges how much she can eat, but deliberate and continual waste would get me.