In update 0.15 you could meet them by doing a series of stuff when you go to the mansion.
Here is what I wrote in a comment for that release:
"You have to pick the option to buy the counterfeit invitations.
Then when these two options appear 1) "Kill the Councilor" and 2) "Jump off the balcony". Pick them both only once and then choose the option to back out so the MC doesn't die.
(I think you can alternatively also choose the option to "Jump from the Balcony" twice and back out both times, since the check looks to see if you picked a "cursed" option no more or less then twice.)
If you did it correctly when you leave the mansion, and speak to the skeleton guy again ask to "Recruit him". Then after a bit of dialogue a special scene should occur before the MC gets back onto the ship."