Risks for filing I485 separately between principal and spouse

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[Ik1983]

Principal Details:
I-140 approved, EB-2, ROW, PD is 3/10/2014

Spouse Details:
Married since 3/31/2013.
Entered US on 05/2013 on H4.
Changed status from H4 to F1 on 09/2013 while in US.
Went to India on 12/2013 and got a visa stamp and returned 01/2014. Visa valid till 2018.
She is graduating on 05/2016.

Questions
My wife is travelling to India on 12/8/2015 and returning on 1/5/2016.
Since we won’t have enough time to get AP, what options and risks will we face if we have to file for I485 separately?

Overall I see 2 scenarios:
1. I apply in November, my wife travels and returns in January. She waits 90 days and then applies in April to avoid any fraud.
a. Is there a risk at POE when she returns in case my I140 / I485 somehow comes in her system?
b. Is there any other risk if she applies for I485 in April?
I am assuming PD will be current in April as it has been like this for a while for EB2, ROW category.
2. My wife returns from India in January and then I will apply. She waits 90 days and then applies in April to avoid any fraud.
a. Is there a risk at POE when she returns in case my I140 somehow comes in her system?
b. Is there any other risk if she applies for I485 in April?
I am assuming PD will be current in April as it has been like this for a while for EB2, ROW category.