I have the following formula
=TEXT('Non Productive Aux'!B25/86400,CHOOSE(MATCH('Non Productive Aux'!B25,{0,60,3600},1),"hh:mm:ss","hh:mm:ss","[hh]:mm:ss"))
which I now want to amend and insert the following into the formula above replacing the bits I have made bold
=SUM('Opmis MPP...