Maps changing

[Phazite]

Okay, in some quests things can change after you do something like beat a dungeon. Like in Tortuga after you beat a dungeon the town changes. The only way I know how to do this is warping to different maps and Dmaps after you get the triforce or go in some kind of warp, but then there is a problem. I can't hide heart pieces anywhere or someone could keep getting it in all of the maps every time they beat a dungeon. Is there a better way to do this?
Sorry if that was confusing.

[Freedom]

In Tortuga there are 9 towns that look alike, and beating a dungeon sets direct warps in the path leading to the town by using the boss flag from the dungeon you beat.
so since each town is different, then you place whatever items you want in each one.
In the enterance screen to the town you can warp to as many as 9 screens just walking across that 1 screen, but since it's a direct instant warp you don't even know you are warping.

The first town is level 1, and beating the boss in level 1 triggers secrets placing the direct warp in the town enterance screen path which then warps you to town level 2, and so on.

In that enterance screen (all 8 of them) is a trigger enemy that dies when the Boss to the level is killed, and in screen data you set enemies = secret which places the warp tile, you also set no secret sounds, and set the boss flag in enemy flags.

[Phazite]

1. You need 9 towns and 1 of everything else then?
Do I put 8 or 9 trigger enemies on the entrance screen and when the boss dies in a dungeon one of the triggers die? How does the warp go to the right town and go to the right spot on the entrance screen?

2. Is there a way to change the overworld like that? Like after you beat a boss it's raining and some enemies are different but you can
still find hc pieces in the place they usually are.

[Freedom]

I started to try to explain again, but then reread what I posted above, and I really can't explain it any better then that.
1 trigger enemy per town enterance warp screen, you don't need to set up warps for town 9 since it's the last.