Function to understand blank cell for no digits (time),#value# , & time overlapping

Hi Experts,

I am facing three issues , when "if" function is used to add time the cell remains blank and time is not shown.
second issue is for result to remain blank instead #value# results
Third issue is overlapping of time before first item is finished,

Attached file has details please see remarks challenges is faced by me.

Currently I fill details manually

Thanks
Karnik

Hi AliGW,
Thanks for looking it;
Issue 1, How do I get result in cell D3 as 9:37:46 and cell does not remain blank
Issue 2; how do i get results in cell D4 to remain blank without#value#

Issue 3: if column D has time value (not blank) than to be added in added in C column time + 2 min

let me elaborate issue 3;
Cell D12 time shows 10:04:12
but in cell C13 time should show only after D12 time and not before (C13 shows 10:00:03) , it may show 2 minutes as 10:06:12,
How do i add time in C13 2 min if cell D12 has time shown and not blank

if issues 1,2 are resolved may be I will be able to solve with limited knowledge

Thanks once again

Hi Glen,
Thanks for suggesting simple function to my complex issue....
Saved huge amount of manual time!
Cheers
Karnik

Hi Glenn,

Wondering what is digit 1440 in the function, is it some constant?
Also if I have to add one more item "ZZ" as OR besides "Z", how do I re-arrange the same function?
Thanks in advance,
Karnik