please help do i have any custodial rights?

i have a sister who suffers with bi-polar disorder (manic deppression) she has a 4 yr old son(who addresses to her by her name and not mum) and they both live with me, my daughter who is 9 yrs old and my partner of 4 yrs. my sister often goes out for up to 2 wks at a time with no contact at all, she drinks from first thing in the morning and refuses to send her son to school, the poor boy spends up to 10 hours a day playing on a computer when i am at university and my partner is at work. i was very concerned by this and firstly found a school for my nephew to attend my sister agreed to this as long as i took responisibilty for getting him there. as part of my sisters manic deppression stage she loves getting chased by the police and often goes out for a drive after drinking between 4-8 cans of lager and unfortunately sometimes as her son in the car with her. she has recently met a man who is 60 yrs old (35yrs older) who is an alcoholic and lives in a camper van in a pub car park he has a lot of money and she states that this is the reason for her being with him, she comes home from time to time to take her son up there for a few days this time was especially hard because she had to ask me what time her son goes to bed, what time he has to be in school and what type of food he likes eating. when i picked her son up from school and told him that he was going to stay with his mum he began to cry and said that he didnt want to because he had no where to sleep and we didnt like her new boyfriend. i had no choice to hand him over but did ask her if she would sign over parental rights to me and my partner she not so politely said no, i have not seen my sister or nephew for 4 days now and i know she hasnt taken him to school. i would love to be able to care for him full time as i know my sister is incapable at the moment of being a mum. i am a full time student and in a gay relationship my partner is completely supportive and has a very respectable job. does anyone know if we have any rights please!!!!

[randalljd]

You would not have any overriding rights unless a court intervenes and gives you those rights. But you may want to file in court and seek those rights under the current circumstances.

[missingmyhubby]

[quote=Unregistered;9282 does anyone know if we have any rights please!!!![/QUOTE]
no, neither of you have ANY rights to a child that is not yours. your partner is a legal stranger to the child. where is dad in this?