You can promote different handles under the same Ads account after those handles have been set up as promotable users, a process by which the owner of that Twitter handle grants you permission to use them in promoted content.
There are two types of promotable users -
RETWEET_ONLY. A given Ads account can only have a single
FULL promotable user, the owner of the account, while there can be numerous
RETWEET_ONLY promotable users.
You can check the promotable users available to your Ads account through GET accounts/:account_id/promotable_users.