No it isn't. It's BA policy to ensure small kids are seated near to an adult on the booking; if another adult on the booking is seated elsewhere, so be it. If the whole group wanted to be seated together, paying for seat selection is the answer.

i was flying CAI-LHR-YYZ last month but unaware of the laptop/tablet carry on ban until the day before my BA flight when I received an email "reminder" from BA about the middle eastern airports this was still in effect. Like most, I thought the ban was over at the same time the US removed it. (And I had earlier in the month departed on RJ twice from CAI and AMM and had no such restriction.). I didn't like the idea of having to check my roller bag that I had carried on for nine flights prior to this one, but had to, at least to LHR. Nor had I come prepared with a lock for my bag...and none was available for sale at my hotel or airport terminal. I short checked my bag so I could retrieve my Air and iPad at LHR, but decided to recheck my bag since I now had several amenity kits from my previous flights and knew while these easily passed through security in their sealed bags, at LHR they'd be torn apart and the few tubes of lotion and toothpaste forced into my baggy of toiletries! At CAI I "sealed" my bag with a twist tie I had packed away, but nothing was missing from my bag when I got to LHR. As well as enforcing this restriction, we went through a final security check of our carry on items at the gate...this after going through one security check entering the airport terminal, the standard one going airside, and yet another leaving the rather disappointing business class lounge!

As a side note, I noticed on my CAI-LHR flight that the man across the aisle from me managed to bring a CD player onboard and he was using it throughout the flight!