With
Separation Agreements made before March 2003 the courts maintain jurisdiction. Under s1 Family Law (Scotland) Act 1985 there is an obligation of aliment by "a person" who has accepted a child as family. "Child of the family" means any child that lives with the person on a day to basis as though they were their own family. However, the Act specifies the obligation of aliment shall only be owed by a husband to his wife, a wife to a husband, a mother or father to their child or a person who has accepted a child into the family. See;
www.legislation.gov.uk/ukpga/1985/37/contents
After March 2003 under child support legislation the courts normally have no powers to impose an order for
child maintenance or vary the agreement and the 12 month rule applies. Either the parent with care or the non resident parent can apply to the CSA for an assessment after one year and the separation agreement in relation to child maintenance ceases to have any effect. The CSA can assess a natural parent, they can''t assess a person who has accepted the child as family.
Only when the natural parent has died or lives in another country would the CSA have no authority to assess and collect child maintenance. If the natural parent had died or disappeared a claim could be made on behalf of a child through the courts against the person who had accepted the child as family. The court would then consider the nature and duration of the relationship, in particular if the "person" had assumed responsibility for maintaining a child.
Once children reach 19 years of age or "non advanced" education ends (Advanced Higher level or less, or whatever they are called these days) the CSA has no jurisdiction, the courts do for 18-25 year olds in education. At this stage your ex could apply to court for a variation to the separation agreement and the court would look at yours, his and your child''s financial situation afresh.
Your new partner''s finances would then be relevant in that he contributes to your household expenses, reducing costs and the need of aliment. However, if your ex has had pay increases, promotions or acquired a new partner they would also be taken into account too. A new partner would be contributing to your ex''s household and reducing his costs so that he has more disposable income with which to pay child maintenance.
That''s a bit long winded, but in a nutshell there is no legal provision that I know for a non resident parent to claim maintenance for the children from your new partner.