lake I need help with my cats?

i had 2 cats until just recently when my devorced-with-my-mom dad, gave me tiger..... spencer (male) and kit-cat (female) seem to not want to fight, and seen to be talking to eachother, but everyonce in a while a fight breacks out, i had been advised to just let them run free, and theyll learn to like each other, but im not sure, i dont have any room space to put tiger (male, forgot to say) in alone....should i keep doing what im doing or what? i also have 2 dogs that run free in the house (male and female sheetzu's) that need introducing to tiger.....can anyone help me?there