Yes, I also have the problem when displaying both maps at the same time (Cayo Perico and San Andreas), the bridge passes under Cayo Perico. I assumed there was a way using a script, that’s why I didn’t modify the GFX, but if there’s no other way I’ll modify it if necessary.
If you want to do it yourself, here’s how to modify a GFX file:
It doesn’t have to be complicated, but it is a tedious task.
First, you need to transform your GFX file into a SWF file. To do this, you need to open it with HxD software and modify the first three letters with FWS like that.
Change the .gfx to .swf.
Then you can edit the SWF file with FFDEC (aka. jpexs-decompiler).
When you’ve finished editing, remember to convert your SWF back to GFX in the same way as before.
I hope this has helped you.