Itunes authorization question?

i know you can only have 5 computers authorized to one itunes acount, but how many itunes acounts can be authorized to one computer. because i already have three different acounts authorized to my computer and i would like to make another one. one is my brother the other is my friends and then the last one is my family one. i use my family one but my mom keeps stealing all my money from giftcards to use for her own songs. so thats why i wanna make another and i just want to know if there is any limit on how many itunes acounts a comp can be authorized to.