[spoiler]You can try to make this whole plotline and ending for it make sense but it is impossible to do. Here is where it really gets complicated. In 1840, Angelique releases Barnabas from the curse she put on him in 1795. At that point in 1970, that Barnabas should have ceased to exist and the family in that time should not have known anything about any Barnabas, except the one that lived in 1795. There should never have been a 20th century Barnabas Collins as far as they were concerned. Because he was released from the coffin and released from the curse in 1840 , all events after that point should have been altered, with no vampire in 1967 for Willie to release, thus no Barnabas, cousin from England in 1971.
For that matter the 1897 storyline does the same thing, in that Barnabas of that time is no longer in that coffin and does not return to it for Willie to find in 1967 so at that point the family should not have known him when he returned from that time.
Each time history was changed with the regard to other aspects, it had affects in the present day, but not in regard to Barnabas. In 1840 the changes there to the fate of Daphne and Gerard, cause their ghosts not to come and Collinwood not to be destroyed so why would changing Barnabas's fate in 1840 cause the same alterations in the future as well.
For that reason, I gave up trying to make the plotlines make logical sense years ago and just enjoy the stories.
Raholt[/spoiler]