Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
I do not use Windows, so I cannot help answer your question. But please always provide your IM version when asking a question.
If you use convert ... composite rather than composite, then you should be able to write you several commands as one long command line. See https://imagemagick.org/Usage/compose/#compose
With ImageMagick 7, you should use magick not convert and if you still want to use composite, then it should be magick composite. Syntax has changed a bit for IM 7.