Pathfinder 1st Edition

Is it possible to make a new version of the Pathfinder 1st edition sheet that recognizes all the character classes? 

You can enter any character class's data manually on the Pathfinder by Roll20 sheet (and I expect the same is true of the Community sheet). It is the Compendium and the Charactermancer that lack the data for classes other than the core. I do not know who currently maintains the Compendium or what process is required to add to it, but as there are legal issues (verifying that Open Content is properly labeled, for one) it is not something straightforward. The Custom Compendium suggestion gives me hope that there may be a way (someday... it is taking a long time) to add material at least for your own use. 

Yes and no.  You can enter it manually, but some things do not work properly.  For example, flurry of blows will not work with a brawler class.  Spells for non-core classes are not automatically assigned the correct level when using drag and drop.  Yes, there are other ways like macro coding to get things entered, but they are above the skills of most users.