As Hydqat said, a legal certificate is necessary from the embassy to term them both as husband and wife. Than Qatar government will have no objection to it. If she is already in qatar working with a work visa than it is there is no need to take her in husband's sponsorship when the salary is less. Let them stay as they are independent in their work visas. When children are born they will be in your sponsorship. There are many such marriages in qatar so dont worry.