I concur with John but would like to comment. The two examples you gave are handled differently.

If you try to type Xm7add11 BIAB will not accept it. You have to type a supported chord such as Xm11. You can always see all the supported chord types in BIAB by right-clicking, selecting Chord Builder, and clicking on the pull-down for other chord types that says 13#9#11

If you type Xadd9 it IS accepted by BIAB, but (assuming a recent version of BIAB) is converted to Xadd2. Internally, add2 is the same as 2. You can also enter X2. The reason they are the same is that BIAB has chord entry shortcuts that make this conversion to a chord type that is supported, and, as John said, the 2 chord is directly supported.

BIAB 2025 Win Audiophile. Software: Studio One 7 Pro, Swam horns, Acoustica-7, Notion 6, Song Master Pro, Win 11 Home. Hardware: Intel i9, 32 Gb; Roland Integra-7, Presonus 192 & Faderport 8, Royer 121, Adam Sub8 & Neumann 120 monitors.