michele – it’s as well that you took the initiative to search for Special By-Laws (SBL) because that was going to be my next point of advice once you confirmed residency status, and if the SBL of relevance that you found has been properly Registered (on the Strata Title), then that tells me that noise transmission from all Lots except those on the ground floor must have been historically problematic, and that both you and your neighbour are legally required to abide by the provisions of that SBL.
The only way around that SBL would be to as you suggest arrange for a new one with different provisions or to amend the one that’s existing, but as both of those options would involve the drafting of a new or amended SBL, and a General Meeting of your Owners Corporation where ≥75% of those Owners in attendance (both personally and by proxy) would need to vote in favour of the proposal in accordance with the unit entitlement of their Lots (i.e. a “poll vote”) in order for it to pass, and with all of that being entirely at the expense of you and your upstairs neighbour, quite frankly I wouldn’t bother; hence my use if the term “rigmarole”.
Right now, and albeit inadvertently, your upstairs neighbour is in breach of the “model” By-Law # 14 that’s provided in Schedule 1 of the NSW Strata Schemes Management Act (1996) that I quoted in my last post, and whilst you could pursue a formal resolution to that by requesting that the Executive Committee of your Plan meets to approve issuing her with a “Notice to Comply” (with a By-Law), if you wish to remain neighbourly why not try an informal approach in the first instance?
Decent underlay seems to me the most neighbourly and effective way forward, as believe me timber flooring, and particularly that of the “floating” variety would not only be contrary to the existing SBL, but would almost certainly make matters worse – have a look HERE for some commentary on timber flooring arising from many posts on this Forum and HERE for some general advice on matters Strata.