XML : iOS9: set XML file association with WPS Office

I have a document saved in xml open format (originally a docx but doesn't matter). I'd like to use WPS Office in all my devices to edit this document. Can do it in Android and Windows, still no success in iOS9.

I have an iPad pro. Downloaded and installed WPS Office. Put my xml document on google drive. Tried and open it, but no "WPS Office" item was shown in "Open in..." dialogue. I've read about info.plist file to set file association, but I can't understand where to find it (using iExplorer and iTunes). Should I create a new one, or what? Thank you all very much.