From the main menu bar, select 'Empires', then 'Systems', then 'Transfer System Knowledge'. On the Transfer System Knowledge screen, enter the empire to 'Transfer To:', highlight all systems, then hit the 'Transfer' button.
On the (F2) 'Population & Production' screen, select a colony of the empire, hit the 'Transfer' button at the bottom, then choose the empire you wish to transfer the colony to. Note that an empire with multiple races (ie different racial tolerances) will have multiple colonies on each inhabited system body - one for each race, to represent the (possibly different) colony costs. Repeat for all colonies.
On the (Ctrl-F7) 'Technology Report' screen . . . you're out of luck, since Steve removed the 'transfer knowledge to selected empire' button several editions back - I think when he added wealth, and the planetary market to sell ships, tech & minerals to other empires.
On the (F12) 'Task Group' screen, on the 'Special Orders/Organization' tab, select a task group and an alien empire, hit the 'Include Commanders' checkbox, then hit the 'Transfer Fleet to Alien Empire' button. Repeat for all task groups.
On the 'Planetary Market' screen . . . you're out of luck, because it's disabled and Steve removed it from 5.0 and up until he can rewrite that section of code.
Miscellaneous: Turn on SM mode, on the main menu bar choose 'Spacemaster', then 'Compare Tech' and on the window use the 'Give Tech' button to give the new race any tech possessed by the old race that they do not already have. Also to give them any race-specific tech you wish, though personally for RST I prefer to make new tech projects with the old race's name appended to the front - eg 'Varosian 4" Rapid Fire VisLight Laser' for what the Varosians used to call the '10cm C3 VisLight Laser'
Wealth transfer is not possible at this time, as I do not believe it's associated with any particular colony.
Finally, go to the Aurora Suggestions forum and suggest that Steve put a button on the (Ctrl-F2) 'Empire Details' screen to automate the entire process of amalgamating with another empire. #:-]
