Disable model updating ?

I would like to test the BGS library for post-processing some short very static sequences.

When I do that with OpenCV, I usually :
-make a first pass with an auto-learning rate on the sequence (or a set of images matching the learning "time window" of the algorithm)
-then I can pick images randomly in my sequence, and "apply()" the algorithmn with a special value for the learning rate (0) to prevent the bg model from being updated any more. ([https://docs.opencv.org/master/d7/df6/classcv_1_1BackgroundSubtractor.html#aa735e76f7069b3fa9c3f32395f9ccd21](https://docs.opencv.org/master/d7/df6/classcv_1_1BackgroundSubtractor.html#aa735e76f7069b3fa9c3f32395f9ccd21))
This way, I have reproducible results that do not depend on the order I look at the images.

There seem to be no such "learningRate" abstraction for the BGS library, and I cannot "disable" the BG model updating.

Did I miss something ?