hi mifta, it happened to my cousin and it got really ugly!! they had a 7 year old boy together. he divorced her and married a canadian woman 4 days after the divorce came though! she was a well-to-do with a high and mighty family back in canada.she was determined to have the kid come live with them. im telling you what that little guy had to go though is something i wouldnt wish on any child! things were sorted out and he stills sees his dad but my cousin has full custody, and he has to run everything by her before he does anything.
please please please tell your sister to get some legal advice ASAP!!
Better to be safe than sorry!
best of luck, hope everything works out x