I do not know who Melton is. So for me, not worth trading Rozier for them.
You've fallen off, Who. He's started the last 20 games for the Suns.
Loosely translated: he's garbage.
Just a general trade suggestion for OP:
The Celtics are (despite what you may think) competing for a title this year. All trades must logically improve the team this year (not shed salary, not give away better players for worse ones).
1) There is no way that you can convince me that Wayne Ellington is better than what Marcus Morris is putting up this year. For example, you cited ELlington as a 3 point specialist. Guess what: Morris is shooting better (44.8% vs 37.4%). Morris is actually one of our 5 best players on the team this year, which is why he is on the starting lineup. Some people (not me) are even saying that he may get a fat contract next season.
2) Terry Rozier, which I agree is not playing particularly well so far this year, is *proven* backup to Kyrie Irving and is putting in about 23 MPG on a stacked team (not the Suns). Should something happen to Kyrie, I have complete confidence that Scary Terry will step up and run the offense. I cannot say the same thing about Melton, and Holmes will not see any minutes other than absolute garbage time. The Suns would jump all over your deal. The GM's secretary that picks up the phone will agree to the deal.
Both of your trades made the team significantly worse.
Hope this helps.