Hi There.
            So so sorry, for your loss. It is horrible when we lose our babies. You said, a fox,
took 2 when you moved their coop. Yeh, we all heard the saying (SLY AS A FOX. GRRRR)
And how true, that is they are so crafty. 5 yrs ago we too had a fox wipe out 16 of ours.
It was my stupidity as one night i had not locked them in their coop. What a site, he got over 6ft wall, but could not get them back over. they were to heavy. We were heartbroken, it took 5 yrs before we replaced ours, but in March, decided to buy more.
My husband built a double coop and large run further down the garden. Joke was we 
did not even know there were foxes around here. For 7yrs we locked them up every night. Until  that one night we did not, and paid the price. Did you lock yours up at
night. ???? Or did the fox find a way to get in for them. ????? As what happened  to
your last 3 has baffled me. Did that fox come back, and they passed with shock. You
said there was no blood or wounds either. Really strange and if they were sick, you would have noticed. My heart goes out to you both, going through it all. I cannot answer what
happened to the other 3  only if that fox did show up, and they passed with shock. Plus
something disturbed the fox, and that is why he left them. I am sure you will have others
with their opinion on here soon, to help you. As for you waiting, that is up to you both.
All i know, i let 5yrs pass by, until we bought more. In which i truly wish we had done it 
sooner. I have 12 hens,(not allowed Roosters) mores the pity. lol  Even though loads,
do not lock their coops at night, i do because what happened 5yrs ago. I  leave my girls free range in the garden, but i am also with them, too. You say your girl is lonely, in
which she would be, but only you can make that choice. If i had been left a few, 5yrs
ago when that fox wiped them out, i think it would not have taken 5yrs before we 
bought more. However seeing the mess he left, upset me so much, (plus i blamed
myself) for not locking them up. That is why it took so long. Even though, our coops /run  is like Fort knox lol  i  still lock them in every night. If you do decide not to wait, 
check your coop is secure, and move it near where you can keep an eye out. We brought ours further down the garden, plus our run has a roof. We live in UK so 
the only predator is a fox, as we live in a village, but still want to make sure. lol 
Good luck in whatever you decide. 
