Hi Lourdes. I'm not a direct descendant of Charles Workman, but his sister was my great-grandmother. If you want to know more about him in the Pacific, see if you can get hold of an old book called A Pattern of Islands by Arthur Grimble, who was a very young colonial officer when Charles had a senior post in the Gilbert & Ellice Islands before WW1. There are cheap 2nd-hand copies available on Abebooks. There are several vivid stories about Charles - he was a highly educated and very charming man, but sometimes dangerous to know!
I'm sorry to hear how badly he behaved in relation to your great-grandma. Did he at least help to support her? Where was she born?
I don't know any more about his daughter beyond what's already been posted here, I'm afraid. I do have a photo of her with her mother, as a child, and could post that if you're interested.
BTW, I don't think Charles Workman's parents were missionaries - his father was a lawyer, I think. But they may have had strong religious beliefs.