Is it possible to add a feature where you can date the characters? And Captain Rais seem like a good character to have sex with but there's no options available either
Priscilla already has a romance path. Rais is getting his in v0.12 (the next update). Charlotte is getting a romance path in v0.14 or so.
You will only be able to romance one character. It’s a pretty open relationship for obvious reasons, but for practical reasons players are limited to one main romance.
There are a lot of posts on my Patreon about the expansion of romances and about Rais’s romance, so you can look there for more details of you want to.