We are a software vendor looking to add MSIX support to our MSI editing/repackaging tool. It is not really clear if the MSIX SDK is the right tool for this. Could you point us in the right direction to be able to edit and build MSIX packages?
Just to make sure I understand, you currently have a packaging tool that allows for editing and repackaging MSI's. You would like to add MSIX support to that packaging tool - such that you can also edit and package a MSIX package using your tool. Is that correct?
The MSIX SDK currently allows you to verify, validate and extract a MSIX package. It is catered to cross plat developers(iOS, Android, Mac or Win7) who want to support MSIX packages in their apps. If you are looking to just be able to package a MSIX package - I would point you to our SDK tool(MakeAppx.exe) which allows you to package a MSIX package.
Hope that answers your question. Let us know otherwise :)