Is it possible to calculate the CPTs over time?

Sorry, this is not an issue but a question, I couldn't find a place for asking besides here.

I created a DBN and I don't know the CPTs of this network, I want to fill it over time, is it possible to do it? If I know for times t-2 and t-1 all the values, to recalculate before time t the corresponding CPTs? Or should I do it manually? (and I do not know if it is a good practice).

Thanks in advance.