Legal Question in Family Law in Illinois

If they obtained a marriage license and had it signed by someone legally able to marry them (such as a priest or a notary), then they are legally married.

You have not provided enough information for an attorney to provide a good answer to your question. The above response does not consider the age of the parties, the competence of the parties, whether either of them is already married, in the event either of them have been through a divorce whether that divorce is final, and perhaps several other factors that would be important.

If there is a question as to the legality of the marriage, then you should consult with an attoney and provide that attorney with all of the relevant facts. A thorough attorney will know what questions to ask. Also, I will point out that the requirements for a legal marriage vary somewhat from state to state, so the above response may very well be accurate in the state of Florida where the attorne who responded is located.