soft synth multi sounds

I have been workin on several songs that end up having 20 - 30 tracks beacese, i have to use a new soft synth to get  differnt sound banks, and I was wounder if there is a way to lets say use zta bank a at 1;30 sec of a song and zta bank e at 2'30 sec ect ect basicly saving memory and less traks, please give a detailed discripon if there is a way , thank you snoots.