STEM OPT to H4EAD and employment continuity

[gcseeker107]

My wife is on STEM OPT(approved her 17 months until Dec 2016) based upon her F1. My EB2 PD is Nov 2010, we were expecting that my dates would become current and my wife and myself will get EAD based upon our 485 and we may not need to change my wife's status to H4B and EAD. But there are lots of chances that we do as USCIS is not moving the filing date that fast.
Now my concern is since my wife is working on STEM OPT and her STEM EAD is approved until Dec 2016, if we file H4B and H4EAD application concurrently will she able to continue her employment. Below FAQ answered by USCIS is bit confusing, as it says she can work until OPT authorization is valid and filing for F1 to H4 and H4 EAD doesn't extend her Employment authorization, but looks like her STEM OPT wont be invalidated until it is approved.
Please advise? if that is the case I would rather initiate her H4 conversion and H4 EAD right away.

From USCIS website https://www.uscis.gov/working-united-states/temporary-workers/faqs-employment-authorization-certain-h-4-dependent-spouses
I am an F-1 nonimmigrant who possesses Optional Practical Training (OPT) employment authorization. Would there be continuous employment if I file a petition requesting H-4 nonimmigrant status concurrently with an EAD?

As an F-1 nonimmigrant who has employment authorization under OPT, you are allowed to work only as long as the OPT authorization remains valid. Filing an application to change status from F-1 to H-4 nonimmigrant status and/or an application for employment authorization based on H-4 status does not extend your employment authorization under OPT or any previously granted employment authorization. If you file a Form I-539 requesting to change your nonimmigrant status to H-4 and you include a Form I-765, we will adjudicate your Form I-765 only after we adjudicate your Form I-539 and grant you H-4 status.

[rahul412]

Once her H4 is approved then she cannot work until her H4 EAD is approved, it's not possible to work without a break.

[JoeF]

That says that they won't process the EAD until the H4 is approved: "If you file a Form I-539 requesting to change your nonimmigrant status to H-4 and you include a Form I-765, we will adjudicate your Form I-765 only after we adjudicate your Form I-539 and grant you H-4 status."

As soon as the H4 is approved, she has to stop working. She can only start working again once the EAD is approved, which can be up to 90 days later.

So, there will be a break. No way around that.