Michael,
I'm not at a computer where I can help you with this immediately. But since you're using Frescobaldi, check out it's Score Wizard. You can use it to create an SA-TB score like this one. It creates the LP structure, to which you then add notes and adjustments. That structure should give you the LP code you can add to this score (if I'm remembering correctly) to segregate those voice parts and get the stems going the right way.
Alternatively, you may could copy the LP code for each voice part/lyrics into the Frescobaldi wizard output. What you may find an advantage in doing this, is the Frescobaldi developers are quite good at keeping FB abreast of LP code advances so it's LP wizard output is very good. I say this as a long-time FB user. I find FB indispensable.
Regards
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“Happiness is the meaning and the purpose of life, the whole aim and end of human existence.”
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