Hi Felipa. I use a set of 5 string banjo strings.(which of course have loop ends) You go for a set with a 0.010 first string. For DAD tuning use the 1st and 5th (which are both the same gauge)banjo strings for the first pair and the 4th for the bass.
You can use either the 2nd or the 3rd banjo string for the middle, I prefer the 3rd, but see which sounds best on your dulcimer.
Hope this helps. This also works for CAD and AAD tuning, but is a bit slack for GAD tuning.

Hope this helps!   

Grahame Hood, Bromley Kent