The two movies are ignored in the continuity of the show.
Cynthia Cidre, the new show's writer and executive producer, addressed this in an interview:
Interviewer: In JR Returns the scene was set for a continuation of the Barnes Ewing
feud. Why did you move away from this?
Cynthia - I was told, not necessarily to pick up where it left off but
not to pay to much attention to the movies because the movies had
tried to wrap stuff up in two hours. But we did not, I have to admit,
although I saw one of them, I did not download it in my brain. I was
really going off the end of the season, I don't pick it up from then,
its now 2012 so we have not seen the Ewing family in all those years
but now we are going to see them and they look good.
Therefore, the two movies were not considered canon. This can be seen in the treatment of JR. For example, in the first film it was revealed J.R. shot a mirror and left to go to Europe. In the second film, he returned and tried to regain his empire. All of this is ignored in the new series.
So the two Dallas movies have officially been retconned and are no longer canon.