As Sweden is a member of the EU, in the circumstances outlined in the question, the correct procedure for enforcing the child maintenance payments is pursuant to Council Regulation (EC) No 4/2009 of 18 December 2008 on jurisdiction, applicable law, recognition and enforcement of decisions and cooperation in matters relating to maintenance obligations (the EU Maintenance Regulation), which continues to apply after implementation period completion day (11 pm on 31 December 2020) under the relevant transitional provisions, which are the Family Procedure Rules 2010 and Court of Protection Rules 2017 (Amendment) (EU Exit) Regulations 2019, SI 2019/517, reg 27 as amended, the Jurisdiction and Judgments (Family) (Amendment etc) (EU Exit) Regulations