Hi I'm in the uk and just wanted to ask if it is possible for me to get full custody of my sister and my mums unborn child as she doesn't know the father to either of them and I already look after my sister 24/7 and my sister even calls me mum and my boyfriend dad and my son bro and I'm having another baby myself in June and I know my mum can not look after these children as she left me when I was born with my grandparents and I'm 20 now and in really good relationship and my sister is really great and intelegent for her age and I worrie if my mum takes her away she will have a bad life like I did any info would be great thanks

Im not up on the specifics of your country but a lot of times the laws are almost the same. So long as your mom agrees then your could adopt. If its like here ( U.S. ) then your going to need to be married for a years time ( average ) and be stable. As far as a unborn child you can't really do anything until the child is born. At such a time she could give the child up for adoption. Again check with your local barrister.
Adoption Information Line- www.adoption.org.uk, The Adoption Web Site