I could see this playing out. Maybe not exactly, but close. Simmons wants to go to LA, maybe his agent told Philly he wont sign. Philly might really like Dunn and would be better for them than Ingram right now, but can't really take him at #1. Boston comes in and makes it look like they are sweetening the pot and throws in an other pick, and maybe Young.
I wonder if the C's get Ingram how that plays out with if they still go after Durant, move him to the 4 next year or the year after if Ingram is ready to start. Or do they decide to go full young rebuild around Ingram and Smart.
Or we just end up with Bender...... 
What would happen were he to refuse to sign? There's gotta be something the Sixers can do in that situation, right?
It goes roughly like so:
As long as the team offers the player a qualifying contract by the deadline (30 days?) then, even if he refuses to sign, they retain his rights for up to a year. If he goes and plays any sort of organized pro ball for another league (anything from the D league to the Chinese Basketball Association to Spanish ACB or whatever) then they retain their rights for up to a year
after his contract ends with the other league. The only way for him to fully shed their rights on him is to refuse to sign and then NOT play organized ball for a full 12 months.
I didn't review the CBA so I may have some details off here or there but that's the gist.
Note: The way a 'stash' works, is that the team and the player already _agree_ that he will "refuse" to sign. They formerly offers, the player refuses and then goes and plays for another team willingly until they both agree it is time (if ever) for the player to join the NBA roster. The Spurs just recently indicated that some player they stashed 5 years ago (2011 draft!!) will finally be joining them this year.