Unfortunately, no. Functions within scripts or keyword tests are project level only.
At least, as they are... You can convert it to a Script Extension which is then made "native" to TestComplete and able to be called from anywhere at any time without having to "include" files.
Or, you can share the script unit between projects or the keyword test between projects simply by using the "Add existing item" context option within the projects.
Automated Testing Evangelists
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