Morning v-zhta-msft,
All good I worked it out, asa per the below.
CurrentLocationDropDown.Items = [1stLocationDropDown.Selected.Value,2ndLocationDropDown.Selected.Value,3rdLocationDropDown.Selected.Value]
I created a button for the 2nd and 3rd locations, hence if the user decides they only have the 1, then it reads as per below.
CurrentLocationDropDown.Items = [1stLocationDropDown.Selected.Value,if(2ndLocationToggle.Value=true,2ndLocationDropDown.Selected.Value,""),if(3rdLocationToggle.Selected.Value=true,3rdLocationDropDown.Selected.Value,"")]