is it possible to put more than one rom on a gba cart?

Before crying to the wolves about piracy
I want to tell that I respect peoples work
but also like to simplify my life when I can
I have 22 nintendo original DS games
and now that the possibility of not carrying them around with me is offered
I grab it
I mean, I have a Flash2 advance ultra of 1G and a superpass
I would like to put more than one DS rom on my GBA flash cart
I tried yesterday but it didnt work
do I have to include a program like a boot file or something?
thanks for your help...

this is piracy and not to be discussed here. If you have issue with it pm an admin who will explain the situation to you.