Picture #8 is unquestionably a Rosa sp. If all the extensive growth originates from this plant, then it will be Rosa sp. also.
The pictures where the thorns are evident appear to also be Rosa sp. as well, but I can't see thorns in all the pictures. There is always the possibility that two different species/plants are represented in these snow-obscured images.
Perhaps Lolbon doesn't need to save all the runners, and could prune off a chunk (maybe a meter or two) and take it inside to comfortable photo conditions and take some good clear closeups of all the plant's parts.
Blackberries and Roses are both members of Rosaceae, both have pinnate compound leaves with alternate arrangement, both have thorns - but both have some features that can help separate if these can be observed.
