Child British passport

Hi guys
My wife is Filipina and we have just got her spouse visa accepted by the British embassy, we also have a 2 year old daughter who has a Filipino passport (never used yet) I have recently obtained a British passport for her so now she has 2 passports 1 British 1 Philippines, we are all traveling to the uk in a weeks time for good and I would like to know if anyone has taken their Philippine born child to the U.K. Via Cebu mactan (as we are) we visited the BI office today and were told that we have to show the immigration officials both of our daughters passports and not just the uk one as it doesn't have an entry stamp in it , has anyone done this already? We were told by immigration we don't need an exit clearance for her or a dual nationality certificate, as long as we show both Filipino and British passports at passport control I'm just concerned that they may ask for something else as well that we don't know about
Thanks guys
Roger

A few years ago we had a similar situation.
I am a British Citizen, then living in Germany. My Wife ia a Filipina. Our Children have British and Philipine Passports.
Going on Holiday to the Philippines. We decided to use the British Passports in Germany, and the Philippine Passports in  the Philippines.
In both countries this was no problem at Immigration. The problem was with the Airline in Manila.
The Philippine Passports didn't have a Visa for Germany. Theoretically we didn't need one, as the Children would be entering Germany on the British Passport.
We  showed the British Passports to the Airline, and after Consultation with a Superviser we were allowed to fly.
So I think it's always better to show both Passports at all times.

I wasn't planning on showing our daughter's Philippine passport to the airline only the British one, its the same airline I always use for Philippines its immigration I'm more concerned about but thanks for the info