my niece

i live in florida and am the payee for my sister & her daughter who recieve ssi disability. my sister is bipolar/skitsofreniac and has been bakeracted twice. she is currently involved with a guy from the internet that is pushing her to marry him. he is a nut case(i have some proof of that). anyhow i want to have gardianship of my niece but am not sure how, if possible and can it b done w/out consent of her mother? I am also wondering should i do the same w/ my sister? she is mentally challenged but capable of a somewhat normal life.the child is 13 and does not wish to hurt her mothers feelings but wants to b w/ me. i am a single parent w/ 2 children of my own. i can prove(w/ hair folical test) the mother has given the child illegal drugs. time is of essence b/c my sister is plotting to leave w/ the cyber boyfriend asap.

You owe it to the child to take swift action. IMMEDIATELY CALL FL DEPT OF CHILD WELFARE. Tell them how you sister is endangering the minor child (drugs and whatever else). If they don't take action within 24hrs, then call the police.