Wanted to put in my two cents. First though, a question. During your 1st visit, did you meet either or both of the ladies with whom you’d like to have your next party? If yes, when you send her/them a description of your party idea, you should ask with whom she’s/they’ve previously enjoyed a two girl party. That way, you can 1) be rather confident about good chemistry and 2) make a short list of backup candidates in case one of the ladies is not available for some unforeseen reason.
As far as describing your party plans to the ladies, just use a few sentences with brief clear phrases (such as role playing, teacher/student, mutual massage, e.g.) or fetish keywords describing generally what you’d like. If either lady is uncomfortable with anything you describe, you’ll surely hear from her and can make alternate arrangements. Save the fine details for the negotiation at the ranch.
Lastly, make sure you call the ranch the day before your scheduled arrival to confirm your playmates’ presence. Doing this allowed me to make alternate arrangements on the spur of the moment and saved me the embarrassment of initially declining then re-engaging potential playmates after a lady had been called away at the last minute.
Hope this helps.