I believe you could accept the A from your top school as long as it is before you have to CTE date. MD traffic rule, once you commit to enroll (CTE) to the school that accepted you (CTE date varies with school), you are required to drop all WL including your top school WL. If you do not drop your WL (all of them) after you CTE to the school that accepted you, that school can rescind the A because they will be able to see all WL that you are holding out for.