There is no automatic entitlement to any monies as there would be if they
were married.
There is a case to be made that by giving up her
own working career (in full or part) to look after the children, your
sister may have an entitlement to some of the assets that are viewed as
joint - such as the property - but the law is decided under Section 14 of
the Trusts of Land and Appointment of Trustees Act 1996 which is civil
rather than family law.
However, it is possible to make an
application under Schedule 1 of the Children Act 1989 for a property
adjustment order to allow the property to be held in your sister's name for
the benefit of the children. Usually a claim under both Acts would be made
and the court would deal with the Children Act claim with the other claim
being dealt with in the background.
Your sister need to seek
legal advice as the law is complex, there are
many pitfalls and the costs can be huge. If she is entitled to public
funding (legal aid) then all the better.
Charles
Forum 
England and Wales 
