Re-stringing a piano in situ is always a bit awkward…
…but there’s plenty of room to set up all the tools for this one.
If the soundboard or bridge don’t need repairing, I always re-string in sections (or, in this case, half-sections) – because removing all the strings at once removes all tension from the strung back (of course).
Totally off-loading all tension from the strung back has a big – and usually bad – effect on the resonant integrity of the strung back: somehow the elasticity and vigour of the resultant sound (and soundboard) is lost – the piano’s tone is aged in one fell!
Doing it in sections is a slower and more awkward operation, but this way is the only one I’ve found to actually re-vitalise the sound.