PLL used for differential interference analysis

I have a question about PLL.
Currently I am performing differential interference analysis using signal generators from other companies, but there is a problem.
The sign of the phase is changed by turning on / off the power supply.
My question is
· Is it possible to control the initial phase and phase sign (positive Θ or negative Θ) when TI PLL locks the phase?
· If possible, is it possible by register manipulation of the IC or is it necessary for external circuit?
Waiting for your answer.

Best Regerds