Each of the four partners fills in their own line, rates everyone, and sends back a short code. Paste the codes here and the sheet turns them into a suggested shareholding, criterion by criterion, so the number has a reason behind it.
Pick your seat, describe what you bring, then rate all four partners. You can come back and change your answers.
Paste the code a partner sent you. Their seat fills in and the split updates.
Waiting for the first input.
Treat this as a starting position for the conversation, not a verdict. If one partner's number feels wrong to everyone, the weights are wrong, and that is the thing to fix.