How to join 2 mpeg-2 files with different frame rate in one title

[leonid_makarovsky]

I have 1 AVI file that I captured from the LaserDisc at 29.976fps 704x480. Most of the footage there is from the film source. However, the very end is from interlaced video source. Using AVISynth and TMPGenc I encoded the main part as MPEG-2 352x480 at 23.976fps (29.976fps playback) and the very end was encoded as 29.976 fps interlaced 352x480. I wanted to join these 2 files, but TMPGenc's MPEG Tools complains that the format is different. Fine. Now I wanted to put these 2 files together in TMPGenc DVD Author. It allowed me to do so. However, when I authorized, I observed the following behaviour:
PowerDVD drops a few frames at the joint point, but maintains audio.
WinDVD and my standalone DVD player (Philips DVP642) silence audio for a split seconds.

Any workaround to achieve a smooth transition? Thanks.

--Leonid