Hi, welcome
I do understand this.
I have bipolar, depression etc and my lovely wife has depression. So we lean on each other when we need to but if we are both down we cant do so. That's when its important to have your professionals available because although help from a loved one is handy and often supportive, we arent therapists so often we get our own bucket filled while giving such support.
In your case its double the stress and I'd suggest that both of these individuals are unaware that even though you are "normal" (lacking a mental illness) you are not superman/superwoman. Anyone can fall into anxiety and depression at any time so it would be an even worse situation if you fell into that category.
I think a meeting with them to discuss this situation is necessary. You can even show them this post if you like.
Communication is the key. From any of you a comment like "I'm not 100% today, I think I need more sleep" or similar relay of mental condition is needed.
I can say that my thoughts are also that family members in the same business is a risky venture and with two members with such illness issues it's not an ideal situation. I worry about that having ran a business myself.
I hope that helps. I've got a link below that I've developed and used for many years that could fit into your 3 way family that might help during times of conflict.
https://forums.beyondblue.org.au/t5/relationship-and-family-issues/relationship-strife-the-peace-pip...
I hope you are ok
TonyWK
