Is there a way to convert progressive 25fps animation to 25fps interlaced in order to perfectly fit to my existing DV PAL (25fps interlaced) footage without jerkiness?

Thanks.

Under Field Options you will find: Interlace consecutive frames.

No. Result is still choppy.

Try dropping the footage into a 50 fps comp and exporting to an intermediate AVI file at 50 fps. Don't frame blend or interlace for the export.

Import the 50 fps AVI file into AE, add it to a PAL DV comp, and *then* make sure to set the field options to Interlace Consecutive Frames.

I found the way to convert it with Twixtor which will results with better frame blending than built in Pixel Motion within AE. Twixtor has less warping in movements interpolation. But principle is pretty much same as JeffB described.