Firstly you have my sympathies - the redundancy consultation process is never fun, it's stressful as all hell (Been there, done that!)
I was thinking if I could put forward a suggestion to make everybody’s role as part-timers (proportionately) so that job loss can be avoided.
This isn't a bad idea exactly.. but before you can even float this idea with the company I'd suggest talking about it with the others in the team. Because if they aren't all on board it's going to be non-starter. Assuming you are all financially equivalent (get paid the same, produce the same revenue for the company) then you'll need everyone to go to four days a week - and agree to a 20% cut in wages to match in order to make this the same as one person being made redundant. Unfortunately that's going to be a tough sell - not many people are in a position where they can afford to drop their wages by 20% on-going, and all it takes is one person in your team to be unable to afford that hit and you're back to square one. Or if one person in the team is feeling pretty confident they won't be the one to go, or one that is confident they can get another job easily enough at comparable wages then, well you're back to square one.
Kindly suggest how to put it forward to the hr/management.
It (and it's a mighty big "if") you can get everyone in the team on board then you need to all approach management as a group and propose it as a solution. You'll want to have come up with a workable way that the part-time aspect happens as well - this would need to be presented as a solution rather than "here's a different problem".