The issue is that no matter what the paper will never match since wallpapers like many things are run in batches in dye lots so unless you buy all new paper ypou will never match the dyelot If this was my house I would remove the paper you have and have the walls faux painted to look the same since that is what it looks like anyway.

Understood Patricia. But the cost of labour to do a Venetian plaster effect wall for our whole hall is not something we can do at the moment. And as no natural light shines on the wallpaper we feel like a wallpaper match would work from a different batch, as the bit we need to replace is by a small change in width of the hall, slightly set back, so the light is different there, and no light fitting above it at all anyway.