Keep variables when installing skin

[balala]

Hi everyone,

My turn again to ask a question.
I want to create a skin installer. In the @Resources folder of my config I have a few .inc files, storing some variables, used by different skins of the package. In the already installed config there are some .inc files, which store variables which doesn't exist in the files included into the skin installer, but when using the installed skins they are added one by one regularly. If I create a newer version of the skins (package) and want to upgrade the existing package, I'd like to keep the existing variables, which in the files included into the installer don't exist yet. Note that the files storing the variables exist in both, the installed config and the installer, just the included variables are not present into the installer. Is this possible?
I tried adding the files to the Variable files field of the Skin Packager, but no succes: when installing the skin, for the variables which exist into the installer are kept the existing values, but the variables which don't exist into the files of the installer, are removed. I also tried checking Merge skins, but again no succes.
So is there any possibility to keep the values of the variables which in the installer package doesn't exist yet?

Thanks for the help.