H1 - H4 Dependents Travel - during visa extension process

[Thiruarv]

Hi

I have valid visa upto 13th June 2017. Now my visa extension is approved
upto 15th Dec 2018.

1. I have received I-797A approval notice for visa extension upto 15th Dec
2018

2. I have received my spouse I-797A approval notice for visa extension
upto 15th Dec 2018

3. I am yet to receive my son's I-797A approval notice
for visa extension upto 15th Dec 2018

In this scenario, my spouse and son are traveling from India on 28th April
2017 and returning on 29th May 2017.

The travel date falls between first visa extension period and they have
valid stamping for that. They have also traveled two times earlier.

Please give some views about any documents they have to carry or they have to complete stamping and travel ....


Regards

Eswar