Under the provisions of Clause 2 Article 1 of the Law amending and supplementing a number of articles of the Law on entry into, exit from, transit through, and residence of foreigners in Vietnam in 2019 (effective from July 1st, 2020), a foreigner may be considered having his/her visa repurposed when having documents proving that he/she is a parent, spouse, or child of0 the sponsor.
Therefore, your visa can be considered being repurposed from DL to TT if you are sponsored by either of your parents.
