Throw in. Ball barely comes in, and is rolling down line. While part of the ball is over part of the line, a sub helpfully grabs the ball and tosses to a teammate for the new TI. Under the amendments over the last couple of years, with recent changes, is this a DB or a FK?
DFK would be the answer. Here is the appropriate text from Law 3 regarding interference by a substitute in this case. .
I once had this happen with a sub who was on a yellow. He caught the ball clearly in the FOP. I did not 2ct.
I know this isn't very useful but there was a clip I saw making its rounds with this situation. In this particular situation a substitute warming up next to the corner flag and goal line stops a ball that was obviously on the goal line and inside the line that defines the FoP and penalty area. The referee calls a PK and gives a caution.
Bad Ref. As I was setting up the DB, that nagging thought--"wait, was that part of that change?!?" *sigh*
I remember many, many years ago with a u12 game. The ball is rolling down the touchline. The helpful coach picks it up. We didn't give yellow cards to coaches then, and I don't remember if I gave him one. If he doesn't know he can't touch a ball on the line, he couldn't know the proper restart. In the spirit of the game, I had a little talk with him and gave a free kick.
I was reffing one of my daughter's U10 games years ago (assigned ref didn't show up) and this happened. One of the girls picked up the ball. I gave her a tongue-lashing by name, maybe a bit too harshly. Then restarted with a dropped ball. That was before all these new-fangled changes that make indirect things direct, turn drop balls into free kicks, consider non-players equivalent to players, etc.