Can I switch my work visa from Company A to Company B without leaving Thailand?

Hi everyone, I have a work visa for company A and have one year work permit for both company A and company B. Both companies are same ownership but with different objectives and company A wants to slow down operations so they want to end my employment (and work permit) for company A and make company B my main employment. Since I have work permit for both, is it easy to switch the work visa I got for company A to company B without having to leave the country? Thank you!