Dates issue in membership type upgrade

An organization has two membership types: free and paid. When a member wishes to upgrade from free to paid mid-term (i.e. before renewal date), the only way for the upgraded membership expiration date to be set properly is to create a second membership (pseudo) "organization" and assign the higher level membership type to that "organization." Otherwise the upgraded term is added to the original term, effectively giving the member a new full term plus whatever was left in their original term, but all at the higher level. (So, if someone upgrades on day 1 of a 1-year term, they get two years at the higher membership level, instead of the one to which they are entitled). See later parts of discussion here: http://forum.civicrm.org/index.php/topic,27701.0.html