Home umpires as 3rd Umpire

[Gunner_Mania]

I was looking at the last 6 series - IND-SL, SA-Eng, Aus-Pak, Aus-WI, NZ-Pak, Ind-BD. Other than the series involving India neutral umpires were used a 3rd umpires. In the Ind-SL series we had an India TV umpire and the Ind-BD series has Bangladesh umpire as TV umpire. Anybody knows why there is no consistency and also who makes the decision on 3rd umpire. I thought the ICC allocate the umpires for the series and the home board had nothing to do with it.