Can I upgrade to a ChatGPT Team plan with fewer than the stated 5-seat minimum?

One member discovered that it was possible to upgrade from ChatGPT Pro to Team with only 2 member seats instead of the advertised 5-seat minimum. Results seem inconsistent: some members reported they could do the upgrade, others could not, and it's unclear whether this depends on account type or how the account was originally set up. The suggestion was for anyone already on Pro to try the upgrade path themselves to see if it's available, since it would let a solo practitioner or very small team get Team-tier features without paying for unneeded seats.