Entering UK on 2nd passport while waiting for visa renewal?

[funkyr]

I have a work visa recently extended until 2015. My family (wife + 2 kids) have not yet renewed their visas for 2015 so theirs will expire early July 2013.

All my family have 2nd schengen passports from another country (non EU).

We are planning to go overseas in July.

I will be applying for my wife's + 2 kids visa renewal via post soon and am afraid I wont get them back in time for when we leave in July.

If we do all leave for overseas and when we come back will my wife + 2 kids be allowed to enter the UK as tourists on their 2nd passports? Will the UKBA know about the pending visa applications?

Thanks

[Mr Rusty]

What's a Schengen non-EU passport?