Hello,
Ok, but I'm going to answer you anyway :)
This can't be done only by path expression, because there is one more level between current
Street document and required
Room one (in your example this document is
House). If the path would be the same and always with the
House level, then the
Path property could be
/{0}/{1}/House/Room/% and this would work. But the
Path property can contain custom macro, which would find the right path to your images, so it can be done by
custom macros.
Best regards,
Jan Hermann