Drawing on TIFF with Alpha Channel enabled

[mackermedia]

I am working to use mogrify to modify a source template image to do a number of different operations: add background color, add text, add image, etc.

I have the operations working successfully when I start with a source tif that is all white and has no Alpha Channel enabled.

I now want to be able to start with a fully transparent source template file, apply any of the operations, and save a new image with transparency.
The problem is, now that I'm starting with a fully transparent image, none of the same operations are affecting the image. The output is always the same fully transparent image.

Do I need to do some conversion of the source file before attempting modifications? Should I be starting with a different source template file and converting to TIFF at the end?

Any help will be greatly appreciated.

[mackermedia]

Turns out, simply starting with a fully transparent .png image and applying the operations, then saving as .tif works like a charm.