IF you go ahead just be carefull sheep lambing on good grass can get over fat and have very big lambs which for a first timer can be really serious
We wish, don't we, Graham!
I assume there's no paint mark on the lost ewe? In my bit of Cumbria we all mark our sheep with a certain colour in a certain position (our neighbour is blue left thigh, we are red or green right shoulder) so we can all tell each other's sheep at a glance. And she's not horned? Some farmers put a mark into the horn - we used to, on the moorland farm. Some farmers use coloured paint, some strips of colour, some burn a mark into the horn.
My concern about tupping the hogg now would be too large a lamb as the mother will be on better fodder while growing the lamb (even where you are!
), plus the lamb will still be quite wee and vulnerable going into winter.
If the lost ewe is in lamb, you could keep the lambs, or one of them, as company for your hogg. Or get an orphan lamb to rear to keep her company.