If you really want a miko-PD combo, you are inclining to DPS builds so adding support for seems not optimal for 3rd class.
Assuming you got PD vv, you can try the following builds:
Miko/PD/Crusader - miko sweep boost magic circles of crusader…and crusader arts on chant has some little heal for PT(can be count as support lol)
Miko/PD/Exorcist - exorcist entity boost miko Hamaya, it hits like truck. And you get good aoe low cd skills with exo, good for mobing.
Note: if you don’t have PD vv, i would say its not worth to get PD on the build.
But if you really insist to get Miko - PD together and you want a support type, you might try to add Diev.
(this is purely Theorycrafted idea - haven’t tested, haven’t seen any, but might work based on paper)
Be an owl statue summoner(max owl, max clap), and focus your PD skills on support skills like healing factor, modafinil, Fumigate, and Methadone. You can still max BDS with that, and adding the Owl statue and hamaya, you can do DPS while healing and buffing.
With that, you are a bit of a buffer(diev miko), a bit of a healer(healing factor with arts) and a bit of a dps(Owl, hamaya, BDS)