To be brutally honest, I have to say, that Full Disclosure right at the start, while it seems "interesting" kinda makes no sense.
Let me explain.
At the start of a relationship, we are in LUST, not LOVE, it is pure and simple LUST. We looked at them, they looked at us, we liked what we saw, or, at least didn't dislike it too much, and we wanted to see if it feels as good as it looks like it will. Sometimes it does, others, oh NO, get outtta here... At this stage, there's no need for Secret Trading. Some basics are recommended, like relationship status. But that's about it.
Then things start progressing, sometimes slower, sometimes faster, feelings evolve. But it still isn't LOVE, it's something akin to FWB. We are still in LUST. We are still engaged in biological needs modes. Some disclosure needs to happen, to build trust, to build connection, to build "something" that at this phase is still amorphous, still frail. For some, this phase lasts a few months, others days, to very few, only hours.
The big changes start to happen, both start to feel the "indispensability" of that other. Missing their touch, their presence, their voice or their noise. That's LOVE starting to wake up along with LUST. At this point, long conversations and disclosures are needed. Full? No. Just as far as your built trust allows.
This is where Alex and MC are. The deeper they'll connect, will depend on their communication, not the other way around. Trust needs time to build. It also dies, instantly, very fast.
At this point, I (and this is my very personal view) feel that the throuple needs to spend time together. Getting themselves used to and later addicted to each other. This means being coated by each others saliva by talking for hours in close proximity. Talk about what? Well, they need to build a rapport. So, talk about EVERYTHING. From socks colors to rice recipes. Interrupt each other. Tell jokes. Make temporary alliances, to break them 5 seconds later, and do it again, and again, and again. It's not only the girls that need to bound, they all need to bind themselves to each other.
Maybe I'm wrong, or getting to this from a perspective that isn't the one you expect, but, I feel that Alex, Isa and the MC, each have deep wounds and scars. We know a bit about the MC ones, some of Alex's ones and have been hinted about Isa's ones. It is unreal that either of them would go for a Full Disclosure at this stage. Each of them have trust issues. It's not only Alex. Each of them have secrets. The MC is probably the worst offender even.
Yes, BTT, they do need to TALK, a LOT. Like I said, bathe each other in saliva from all the talking (an yes, that is a thing, check it out). Are they at the Secret Trading level yet? Not really. There's loads of basic knowledge about each other to go through first. Well, unless the secrets aren't of immediate concern, like relationships, health issues, or something on this level of immediacy.
So, Dark and Old Aussie, relax, we aren't there yet. It's coming. But there's no reason to distrust just yet. Yes, I know, we have been letting our feelings evolve, we've had Time. They didn't, barely a week has gone by for them. IRL, we would maybe not even have kissed.
Time moves differently here. OK?
Peace