You have to use Guitar Pro music composer if you want transfer audio data from .gpbank audio banks and save them in one of the existing Guitar Pro projects files. GP3 is a bit outdated project version, the latest version uses GPX format.
Convert Guitar Pro audio bank to Guitar Pro 3 project.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert gpbank to gp3 on Windows
Multi-track editor and music composer for guitars
Convert from gpbank file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.