They need to speak to a priest both for advice and for Confession as Catholics in a civil marriage without dispensation are committing fornication. It’s sad that ‘convenience’ motivates their choices. However their marriage wasn’t valid.
Canon 1108.1 Only those marriages are valid which are contracted in the presence of the local Ordinary or parish priest or of the priest or deacon delegated by either of them, who, in the presence of two witnesses, assists, in accordance however with the rules set out in the following canons, and without prejudice to the exceptions mentioned in cann. 144, 1112.1, 1116 and 1127.2-3. [Code of Canon Law]
A valid Catholic marriage results from four elements: (1) the spouses are free to marry; (2) they freely exchange their consent; (3) in consenting to marry, they have the intention to marry for life, to be faithful to one another and be open to children; and (4) their consent is given in the presence of two witnesses and before a properly authorized Church minister. Exceptions to the last requirement must be approved by church authority.