Single & Multiplayer?

Hello there!
I want to make in my game some levels that are only for one player.
I tried it: (Create in obj_other)

if room == rm_multi1 or room == rm_multi2 etc.
{
sprite_index = spr_other;
}
else
{
sprite_index = noone;
}

But it didn't work. And second problem is i have always same sprite in my object (obj_hero) and the other player object (obj_other). How to change another player's sprite? And how to "hide" player in some levels?

Edit:

I think, I can set sprite of obj_hero to no sprite and then in obj_controler draw sprite for hero in hero.x and hero.y and same for other. But is here possible any other methode? Because, when I want to do this what i wrote I need to change more than 20 lines of code, which will not be so fun :/ Please reply!



Sorry for the question; I don't know English very good, so I can't understand documentation really good.