Here's how I would have it play out.
Show up with Tommy (legend), Isaiah (current face/all-star), Avery (All-defensive 1st teamer plus UT guys play ball every summer), Crowder (just because I think KD would appreciate him), and Jaylen Brown (symbolizes the Brooklyn picks we have coming, and future hope), and then of course Danny, Steven, Wyc, and Pags.
Have everyone meet with him quickly (quick daps, bro hugs, hand shakes). Then let Tommy, Danny, Stevens, and Isaiah do most of the talking with the presentation revolving around the past, present, and the future. Have the presentation end with a video that highlights our 18 chips, showcases the greats, shows KG's anything possible, and has the returns of KG and Pierce and the crowds admiration towards them. End with the image of KG shedding tears while watching Gino during his last visit, with chants of Let's Go Celtics in the background.
Then ask KD what he wants and who he wants to play with. Horford. Done. Perhaps Dwight. Done. Westbrook in a year instead. Will do.
Finally, tell KD "We brought a Jersey for you to try on." In walks Reggie Lewis's mom carrying a #35 Lewis jersey and she hands it to KD and says "I would be proud to have you continue what my son started."
Place contract in front him. Signed!
Ok that might take more than two minutes.