Help my sister

So my sister got her self into a complicated situation. Her name is Ana Paula and she has two kids Charlie (9 years old) and Maria (4 years old). 
A couple years ago when Charlie was only 4 years old his father (who is Brazilian) took Charlie to Brasil. He was only supposed to stay there a few months but ended up staying 5 years...
My sister is still married to this man and could never do anything about it legally. During those years she got involved with someone else’s and had another baby (that is Maria).
Earlier this year she got the opportunity to go and see her son for the first time in 5 years, so like any mother would do she took the opportunity and went to Brasil with Maria.
Since she’s been there a lot has happened to her. All she whats to do now is come home. But she needs help to do so, because the people (the fathers family)who were so kind to send her their in the first place now want to keep her there like they did with Charlie.
She was able to complete her goal that was seeing her son and have her children meet.
All she wants is to come home and escape the living hell she unknowingly put herself into. To do so she only needs 1500€ to be able to buy two tickets from Manaus to Portugal. 
If anyone can help even with 1€ We are thankful. 
I just want to be able to see my sister and Maria again and not have what happened to Charlie happen to them.