Multiple Minecraft

Okay, so my mom, my three brothers, and me all play Minecraft. Of course we have one Minecraft with only the shelves mod installed. I can't get any more to work without it crashing it.

My mom paid for it, so I can't just take of the mod because she is using it in her world.

My question is, can you somehow make more Minecraft.jars and how 3 seperate games so we can all have our own mods?

Thanks for helping me out guys!