annex
/ə-ˈneks/
verb
to incorporate (an additional geographic area) within the domain of a country, state, etc.
to add (something) to something earlier, larger, or more important —often used with to
to obtain or take (something) for oneself
The U.S. annexed Texas in 1845.
noun
something annexed as an expansion or supplement: such as
an added stipulation or statement : appendix
a building that is attached to or near a larger building and usually used as part of it : wing
approved the annex in the treaty