I leave in tulsa OK and I adopted 2 kids and there biological grandmother leaves in Alabama and I wanted to do a joint agreement with her. Is it possible that we will be able to do this or what are my options

Once you adopt, the biological family has NO legal connection to the children.

I have heard of court-ordered visitation for biological grandparents after an adoption, but never custody.

I would really suggest you contact your lawyer regarding this, as I do not think you can share custody with her, but may be able to set a legal visitation schedule.

I leave in tulsa ok and i adopted 2 kids and there biological grandmother leaves in alabama and i wanted to do a joint agreement with her. Is it possible that we will be able to do this or what are my options

Let me also add that "custody" can be used to define different things. There is legal custody, which is the right to make decisions for the minor child(ren); there is also physical custody, which means the parent has the right to have physical placement of the child.

As Synnen already pointed out, it would be strange for a court to allow a grandparent to have legal custody of the children if you are already their legal parent. You should, however, be able to exercise a visitation agreement so that the children can still spend time with their grandmother.