Do you mind if the resulting footage has a slight slo-mo effect to it? Does sync-sound matter? Is the main project interlaced? Does the Sony footage have interlacing? If the answer to all questions is no, you can conform the footage with these methods:
Using Compressor:
In the video settings tab, select the codec (ProRes I hope) and change the frame rate to 25.
In the Frame Controls tab at the bottom select Rate Conversion/Best.
Click the very bottom button that says, “so source frames play at 25”
Output at 100% of source and yer good to go.
In Cinema Tools:
Open the clip in Cinema Tools
At the bottom right of the viewer, select “Conform”
Select 25
Hit “Conform”
WARNING: This will not make a copy, but will alter your clip.
This will also resample your audio to a sample rate other than 48 khz. You either have to delete the audio track or resample the audio in Soundtrack Pro to 48khz and marry it back.