How do I make my ligatures show by default?

[Typotron]

I want to substitute a code with a symbol and I have created a ligature substitution lookup table which works well in the preview but not when installed on the system and displayed in software packages. If I add the table to the Standard Ligatures then they will show in Word when I enable ligatures. However, I want these to be on by default without having to enable font features since font options are not available in the software we want to see it in.

I know it is theoretically possible because I experimented with a website that creates icon fonts from svgs and the ligature substitution was fine.

Do I need to add the table to a specific feature that is enabled by default? Or is the glyph naming critical? It has to be TrueType.

It's a steep learning curve and after fours days of wrestling with it I have concluded it is beyond my current understanding. Any guidance will be truly appreciated.

[Bhikkhu Pesala]

Try using Required Ligatures (rlig) instead of Standard Ligatures.