Split it fairly. Prove it after.
You list what's being split. Both sides then share 1,000 points across the parts privately, more points on what they care about more, each through their own link after the deal is created. You get a split neither side can envy, and a signed certificate that proves exactly how it was computed.
One private link per side.
The link is the invitation and the only way in. Send the other side theirs any way you like — and open yours to seal your own valuation. We store only a hash of each link, so a lost link cannot be recovered, not even by us.
Yours
Theirs
What happens next: you both seal your valuations through your own links, then each come back to the same link — in the same browser — to open. Opening is automatic once you're both sealed; then the split computes and the certificate is issued. If someone seals and never comes back, the deal voids and names them.