To set the list of subplans, which current account can assign, use the command account/update_sub_plans:

svc=account/update_sub_plans&params={"itemId":<long>,
				     "plans":[<text>]}

 Attention!
Current user can assign only available for him subordinate plans. To assign a billing plan to an account, the current user must have the right to manage this account (see Access flags: Resources). Besides, the current user must be a direct or indirect parent of the account.
This command is available to execute if the account already has dealer rights (you may use account/update_dealer_rights command).

{}	/* empty object if execution successful, if not - error code */