Let me make it simple.. it must be a 3 or 4 team trade or two separate but immediate trades:
Suns: Ayton $15.7 out, Capela $19m in (not sure if they need to ship out 3-4m in salary to 3rd or 4th team - Haven’t looked at that aspect yet)
Atlanta: Capela $19m out, $12m+ to 3rd team (OR 1-2 players to the 3rd or 4th team.. the teams absorbing salary to facilitate).
3rd Team: $12m player in, TPE with Draft picks to Hawks
They can add a 4th team to take additional Suns salary going out (Saric, Shamet) in exchange for picks + TPE.