Multiple IF condition for time values

[DarkoDeign2]

Hi,

I need help with a formula for cells C3:C7000

in cell B4 I have this formula: =IF(F4="";":::::";LOOKUP(9^9;B$3:B3)+7*OR(B3="";B3=":::::"))
In Cell D4 I have the formula: =IF(E4="";"";C4 + TIME(0; E4; 0))
In Cell E4 I have number values with the ending "min", eg 5 min
In Cell C4 I want to have a formula that: Check if the the cell above, C3 is empty. If true then show the time "10:00", if false then go to next condition.
Check if C4 is empty, if true, then show "". If false show the value from cell D3

Book1
	B	C	D	E	F
2	Date	Start time	End time	Duration	Topic
3	2023-02-15	10:00	11:00	60 min	Cooking
4	2023-02-15	11:00	11:05	5 min	Cleaning
5	:::::	00:00
6	2023-02-22	10:00	10:10	10 min	Walk the dog
Agenda

Cell Formulas
Range	Formula
C5	C5	=IF(C4="", TIME(10, 0, 0), IF(C5="", D4, ""))
B4:B6	B4	=IF(F4="",":::::",LOOKUP(9^9,B$3:B3)+7*OR(B3="",B3=":::::"))
D3:D6	D3	=IF(E3="","",C3 + TIME(0, E3, 0))

Cells with Conditional Formatting
Cell	Condition		Cell Format	Stop If True
E3:E10000	Expression	=AND(ISBLANK(E3); NOT(ISBLANK(F3)))	text	NO
A3:K10000	Expression	=AND(ISBLANK($F3);$F2<>"";$F4<>"")	text	NO

Would appreciate anyones help with solving this.

 

[Jeffrey Mahoney]

This is what I have for Cell C5: =IFS(B5=":::::","",C4="",TIME(10,0,0),D4>0,D4,1=1,"")

 

[DarkoDeign2]

I managed to solve it with this formula:
=IF(AND(E7=""; F7=""); ""; IF(C6=""; TIME(10; 0; 0); D6))