brianswanson200 said "I noticed today that there is no event available for selection on ancestry.com for change of gender or for a sex-reasignent surgery."
True, the MemberTree program only has available a score or so of the numerous standard GEDCOM-tagged events, as predetermined events. Some that I need pretty often, such as Marriage Bonds, and roles such as guardianships, estate administrators and baptismal sponsors, also are lacking.
You can create custom events. But it is probably better in the long run to establish the event properly in a home-computer genealogy program. The MemberTree program has never been intended to be a full-featured genealogy program.