Hello everyone. Thank you all for the kind words.
I've been putting off this post for a few days because I just wasn't ready to "talk" about it yet.
We decided to go ahead an put Maude down without first lancing/investigating the lump. This turned out to be the right call, and I'm really very glad I didn't put her through that added stress. I opened it up after she was gone and it was a tumor.
So we have 6 girls left, and have come to a decision regarding their future: We will continue to care for each and every one as long as she maintains a good quality of life. Its going to be so very hard, but I have agreed that I will not intervene when they fall ill, only be there to end suffering. It goes without saying, I think, they are a closed flock.
@microchick I've read many posts over the years where people harp on how irresponsible it is to not cull the flock in a situation such as this. I want to thank you for your words to the contrary. I will not give up on them out of hand.
I feel the need to add: this decision was also heavily influenced by our living situation. We are fairly secluded and have acreage. It might have been different if we lived in a neighborhood with other chicken keepers, but fortunately, that's not the case. I know some would still argue that it doesn't matter... biosecurity would never be certain... etc. Well, regardless, this is where we are.
Thank you all again for the support.