I have custom style in \themes\classic\resources\variations
And have to manually copy it after AI version upgrade if I choose to save old version and add new side-by-side with old.
Is it possible to copy it in installation process?
If you will install a new Advanced Installer version side-by-side with your older one, then a new folder (named Advanced Installer + version) will be created in the location where the old one is installed (e.g. C:\Program Files (x86)\Caphyon).
That means that there will be a newer folder created for \themes\classic\resources\variations, which implies that you will need to manually copy them once more.
Unfortunately, I am afraid that it is not possible to copy them during the installation process of the newer Advanced Installer version.
Please let me know if there is anything else I could help you with and I will be glad to assist.