I think I solved the question...
While 1040 is moving from Boynton Beach to Miami (boosting daytime power to 50 kW and night power to 5 kW),
1020 is moving from Kendall (a Miami suburb) to Boynton Beach (4.5 kW Days/ 1.5 kW Nights).
That's according to Radio-Locator.
So Boynton Beach keeps its radio service and Actualidad, the owner, gets a 50,000 watt station in Miami (at least in the daytime).
Thanks for doing this research which has spurred me on to follow it up.
It gets even weirder in this three-way game of musical towers:
1. _990 is moving to the old 1020 array.
2. 1020 is moving to the old 1040 array.
3. 1040 is moving to the old _990 array.
So, in effect, 1020 moves down to 990, 990 moves up to 1040, and 1040 moves slightly down to 1020.
Both Miami operations go up in power and coverage, Boynton loses some coverage day and night,
but Boynton's new day coverage on 1020 approximates their old night coverage on 1040.
All this happens
probably without moving a single physical stick, just a lot of coils and capacitors.
Both arrays in Miami have six towers and the one in Boynton has four, and that will accommodate all three moves.
When one thinks about it, this is really a formidable amount of electrical engineering:
Three new stations with six new directional patterns into arrays that are already in place for totally different operations.
Fortunately, all three are within 5% of each other's carrier frequencies.