Could you just ask MD whether she considers this a serious relationship? if she wants it to go any further? Do *you* want it to go any further? What kinds of goals and expectations would you like to have in place?
Is MD a "reluctant talker," or does she like to communicate? Does she mind talking heavy personal stuff? Can you increase the amount of communication with her just a little, at least?
When do you want to define your poly relationship? Do you consider it a poly relationship? Based on what I've read so far, I would consider it a poly relationship. So maybe you can define it right away, if you want to.
Do MD and FJ have a romantic connection, or are they just friends? If, "just friends," then, you have an FFM "V" relationship. If MD and FJ have a romantic connection, then you have a triad. Either way, you can define it right away, if you want to.
Could things get serious enough with MD to consider all three of you moving to a bigger city, where you'll (probably) have more acceptance? On the other hand, maybe it's premature to assume your small town won't accept it unless/until they've had the opportunity.
These are just questions to help clarify the matters. Hope some of this helps.
Love means never having to say, "Put down that meat cleaver!"