Do I need to give every detail or is it okay that it's implied?

My manuscript is in first person split between MMC and FMC. My MMC discovers something that means the plan that they had made for the big final scene needs to change. I haven't said or shown anything in my manuscript so that the reader knows that FMC knows of the new discovery, but because she is integral to the new plan, I'd thought that it was implied that the new discovery had been conveyed to her (off camera). One of my betas has asked if she has been told, so I guess to her, it's not clear. There is a place where I can add this detail but I'm hesitant because to me it seems obvious that she must have been told as the plan can't go ahead without her. Just wondering what others feelings are on this in ya? Do I need to specifically include a part where MMC tells FMC the new plan or not?

Do I need to give every detail or is it okay that it's implied?