H1 employer change, H4 dependent should re-stamp again when travel?

I have changed my employer from A to B and I want to bring my family to US now.

Can you please let me now whether My depedents (H4) should go for visa stamping again?. This is the first time they are travelling.

They had stamping in the month of Apri 2016 with my previous employer and have validity up to 2018 August.

They can travel using old visa stamp. Send them copy of new approval notice and other documents related to new employer.

At PoE, they need to tell the officer that you are working for this new employer and show the new petition. If not, they would issue I-94 based on old employer and not the new one.