St. Georgenkirche Silbermann manual shove coupler

If anyone has actually played the REAL organ, can you tell me if, while playing on the upper manual, it is practical to engage the manual shove coupler with the aid of an assistant(s) without any effect on the performance.

Yes, I can be sort of OCD about "hisorical" performance.

I don't know exactly this organ personally, but a lot of similar historic others.

Usually a manual shove coupler only could be engaged, while not pressing any key.
Otherwise you may damage the tracker mechanism! This means, the shove coupler only can be engaged in music pauses. The use of historic shove couple isn't comparable with modern couplers.