Welcome to FT.

VS is shorthand for Virgin Atlantic, all their flight numbers start VS, like BA is British Airways.

I think from what you've described you need to decide whether you are going to earn enough points from either BA or Virgin in order to redeem them for flights. Bear in mind Virgin is a long haul only airline although you can redeem virgin points via Flying Blue, the AF/KLM Frequent Flier scheme. I suspect that unless you have a lot of spending on credit cards you will find your accrual rate will drop. Previously I think you earned a lot of Avios from your business travel.

The advantage of BA is that you always have the option of their short haul network. I have used 2-4-1 vouchers on BA Club Europe flights rather than lose the voucher but you do tend to get better value using them for long haul.

I think also given the expanded family you will find spending 2-4-1 vouchers increasingly difficult, it's bad enough finding two seats let alone using 2 vouchers for 4 seats (which you can only do with the Premium Plus paid voucher). Also don't forget that under the new rules the 2-4-1 voucher from the free BA Amex is only redeemable in economy.

Also with BA you always have the option of converting to Nectar points and spending on food in Sainsburys. No good if you only shop in Tesco of course.

I would concentrate on the airline you foresee doing most of your travelling and treat any Avios or Virgin miles earned as a bonus.