The banks lent the money to the developers to buy the land, the developers bought the land, the vendors of the land went off to the bank and deposited their money, the bank then lent the money to the developers to build the house, then, they lent the money for the borrower to buy one of these sh1t holes(we wont open a debate about the appalling building standards here). So the bank benefited '4 times' for the one house i.e 3 loans and a deposit. The bankers were the professionals and knew that property was grossly overpriced(both BOI and AIB sold their headquarters in 05 yet bizarrely continued to lend to people so they could buy the grossly overpriced property). Some people were wise enough to know that property was extremely overpriced and refrained, other people were led to believe by the government and banks that they simply had to get on the ladder(now more of a snake i would say!). Ok, I think I am just ranting now, anyway back to your problem of what to do with the 1 bed.
Here is my advice....move out and rent a new place i.e 2 or 3 bed, which is what u need with a family, stop paying the mortgage on the 1 bed entirely, the bank will repossess (dont hand back the keys as ur social housing entitlements will be effected) and sell....eventually. They will then obtain a high court judgement for the residual balance and seek to attach this to any assets you might have - as u are renting u wont have any! Caution - this may not be a suitable plan if u are expecting to inherit ur uncles farm or parents house etc. Yes your credit rating will be shot, but I think I would prefer to have my credit rating shot then share my bedroom with my wife and teenage son...sorry i am not trying to be disrespectful, i'm just lying it on the line.
The only other thing the bank can do with the judgement is to attach it to ur income, however the banks are taking judgement left right and centre at the moment but are not actively following up on these? Why not u ask? Well they possibly might in the future, just doesn't seem to be a priority right now. The main reason the banks are taking out judgments is to keep the 'loss' on the sale of ur house off their balance sheet, judgments, imho, are nothing more than a means for the bank of hiding losses i.e. taking a judgement means its not actually a loss, technically anyhow!
if u continue to rent, a court will have to leave u with enough of ur income to support ur family and u might end up having to pay a small amount towards the residual balance if the judgement is successfully attached to your income.
The other option is to emigrate. One thing I will say however, the banks certainly do have some dam good investigators so dont think they wont find u overseas if they have to, dont fret however as u are overseas, so while they might find u there is little or nothing they can do to you.
Best of luck, I feel really sorry for ur situation.