Taxpayer and her ex have two children (boy and girl) and each get to claim one child every year since 2011, unless ex is behind more than $560 by December 31st each year, according to their legal document. Ex is behind more than the $560 but told Taxpayer he just filed claiming his son for 2020 anyway.
Would the best option be to have Taxpayer go ahead and file without claiming her son, only claiming her daughter whom she's entitled to so she can get her refund which she would like to get as soon as possible (although it'll be late February since she gets EIC) , and then file an amended return later with all the legal paperwork showing she should be entitled to claim her son as well since ex is behind in child support?
Thanks for any help.