That 1901 census return at reply #21 indicates that Annie McKee and family were in the 44th house enumerated in Burnaby Street, which doesn't automatically read across to street number, but when you look at the names in the other households enumerated in that street, there seems to be some measure of correlation between them and the names against street numbers in the 1901 Belfast street directory. With that in mind, note the following listing under Burnaby Street in the 1901 directory:
44. McKee, James, sailorBurnaby Street intersected with Roden Street, so I wondered about the following death of a 44 year old bachelor called James McCabe in 1902, he was an R.I.C. constable and died in the workhouse (presumably infirmary), but was described as being 'from Roden St.', which I'm thinking might simply mean c/o the police barracks in that street:
https://civilrecords.irishgenealogy.ie/churchrecords/images/deaths_returns/deaths_1902/05689/4603510.pdfI know this is speculative stuff, but it's starting to look like we also need to think outside the convention of a marriage and children born within wedlock.