Hello there,
I am sorry to say it would be very difficult to have dependant visas for your parent
s
The main rule is Para 317 of the immigration law which is
not applicable to your parent
s
You need to prove that they are mainly dependant financially on you and there is a most exceptional circumstance and then their dependant visas will be decided outside the rules
It is expected that their visa will be initially refused and there will be an appeal that may take approximately 12 months to be heard. The main issue is to convince the adjudicator of their financial dependency and the most exceptional circumstances. Your capability to maintain and accommodate them in the UK without restoration to public funds must be unquestionable.
The outcome is unpredictable though.
You need an excellent immigration lawyer and to keep your fingers crossed. In my opinion, IAS is unreliable. You will be expected to pay a few thousand pounds for the lawyer with no guaranteed outcome. Please remember, there are two visas here and probable two appeals.
If you wish to proceed, please do not ask them to apply without good preparation from the UK , calculation of the possibilities and plan of action
The Decision is yours
Good Luck