Hi drs8,
I found a sutta that may be relevant to this discussion on how to deal with theros or teachers one followed prior to being exposed to the true Buddha dhamma.
In the Udumbarika Sutta https://suttacentral.net/dn25/en/sujato the Buddha explains the dhamma to an ascetic from a different tradition and after the said ascetic accepts the Buddha’s teachings, the Buddha says the following;
“Nigrodha, you might think: ‘The ascetic Gotama speaks like this because he wants pupils.’ But you should not see it like this. Let your teacher remain your teacher.
You might think: ‘The ascetic Gotama speaks like this because he wants us to give up our recitation.’ But you should not see it like this. Let your recitation remain as it is.
You might think: ‘The ascetic Gotama speaks like this because he wants us to give up our livelihood.’ But you should not see it like this. Let your livelihood remain as it is.
You might think: ‘The ascetic Gotama speaks like this because he wants us to start doing things that are unskilful and considered unskilful in our tradition.’ But you should not see it like this. Let those things that are unskilful and considered unskilful in your tradition remain as they are.
You might think: ‘The ascetic Gotama speaks like this because he wants us to stop doing things that are skilful and considered skilful in our tradition.’ But you should not see it like this. Let those things that are skilful and considered skilful in your tradition remain as they are.”