<<< Charlie, you're talking about the VST Plugin? >>>

No. It can be done within BIAB the program. There are several different methods.

Examine the Record Audio Window.

This window allows you to record whatever you wish directly into your BIAB project.
From this window you can also punch in/out corrections to your recording.
Note the 'Overdub underlying audio' button. Selecting and activating this button allows you to make another recording that BIAB automatically merges into and mix/balances the original recording track creating a new track including both recordings. You can continue adding to this recording as long as you are satisfied. The additional recordings can be anything. They are traditional overdubs. The new recordings can be vocal double, Background vocals or perhaps a live electric guitar solo mixed with the lead vocal recording. It can literally be anything you wish. Anything you wish as long as you're satisfied with the automatic result the BIAB program has provided.

That's one way.

Another is to commit BIAB mixer channels to rendered audio mixes and then import these audio mixes back into your project and continue to add tracks and render additional mixes of new instruments, tracks and sub mixes. This process is the same as one would use on stand alone multi track recorders like a Tascam Porta studio recording with a fixed number of available tracks. On a four Track recorder, record 3 tracks, bounce the three to one and that frees 3 new tracks for additional recording.

The BIAB mixer channel can be used the same way. Because it is digital until rendered, there is no degeneration the way there was using tape. Also, track count is only limited to whatever free space is available for storage. You can have nearly unlimited tracks.

BIAB had this capability long before the VST plug in. It's true that the BIAB mixer has only one audio track, but that track can be used over and over again in a project. Simply convert whatever is on the audio Channel to a Performance Track and move the Performance Track to another track in the mixer. Once all of the tracks have recorded audio on a Performance Track, mix, balance, level and add effects and render this mix to an audio mix. This mix can be imported into the Audio Channel and the entire process repeated again. Files can be stereo or mono.

A novel way to create and arrange a song using the BIAB mixer as if it were a multi track recorder is to make recording mixes by individual instrument. For instance, begin the recording project by creating just the drum kit first. Start with a midi percussion style that includes drums, shakers, tambourines and such and export that mix to audio and import the audio mix back into the project as a stereo audio file, convert the audio file to a Performance Track and move the Performance Track to the Drum Channel. The same technique could be used to create an acoustic guitar mix, electric guitar mix, keys mix, scratch built strings mix, Background vocals mix and so on.

It's a time consuming method that's not going to be everyone's cup of tea and it requires committing to mixes that if at a later point you're not satisfied with something you're in a position of losing a lot of work to go back and fix something.

Also, as you say, there's always the possible need for saving the various takes of a recording.

BIAB 2025:RB 2025, Latest builds: Dell Optiplex 7040 Desktop; Windows-10-64 bit, Intel Core i7-6700 3.4GHz CPU and 16 GB Ram Memory.