Yes you can BT off of a closed card. A BT is just the new lender paying off your debt with the old lender and then allowing you time to pay it off with them. They either send the funds electronically or by mail to the creditor and it is treated like a regular payment.
Is it possible? Yes.
In your case, the issue may be being approved for a card with a limit to actually transfer everything to (unless you currently have a card with that limit available).
Can you list out your cards that you have, bank, brand of card, credit limit, current balance. Also if the account is closed or open, and the current APR you are paying on each.
Many banks allow Balance Transfers, though some don't make them available to everyone. Other banks don't really do any balance transfers, or none after a certain time. By listing the banks and limits involved, you'll get clearer responses as to what is possible.
First, call your credit card that were closed to see if you can pay if off. Credit cards like Discover will allow you to either transfer those bills to Discover or some credit cards will cut you a check to deposit in your bank then you pay off your outstanding debts.
Call those closed accounts and ask them if you pay if off that they will not report those closed accounts as a charge off or collections.
If i alrdy have a card with a balance enough to hold the balance of other cards. How do i transfer the other card balances to that one card?
If you have BT offers you will probably see them in your on-line account. Most CC issuers provide a way to specify who to make payments to online. if you tell us what the BT card is, you might get more specifics.