That's not difficult for me because I have already written some macros for personal use which uses the same technique. Here is the macro according to your example. Make sure - manually or with the macro - that the cursor is set at start of the line with the first variable.

How it works:

The loop needed will exit if the first character of the line is a = because of the line ==================== after your variables. You can use also an other character if the === line does not really exist in your file or use instead of IfCharIs "=" the following code sequence:

IfCharIs "<"
Else

This alternate version will exit the loop, if the first character of the line is not a <.

Inside the loop the variable name <ipaddress1> will be selected and copied to user clipboard 9.

Next it sets the cursor 2 positions to right and selects 10.1.1.1.

Then it runs a replace all with the search string is the content of the clipboard and the replace string is the current selection.

After replace all which does not modify current cursor position it goes to start of next line and if this line does not start with = it will continue.

I'm busy at the moment so I have not inserted extra code for error handling.

And don't forget to enable the macro property Continue if a Find with Replace not found.

InsertMode
ColumnModeOff
HexOff
UnixReOff
Clipboard 9
Loop
IfCharIs "="
ExitLoop
EndIf
StartSelect
Find Select ">"
Copy
EndSelect
Key RIGHT ARROW
Key RIGHT ARROW
StartSelect
Find Select ">"
Key LEFT ARROW
Find MatchCase "^c"
Replace All "^s"
EndSelect
Key HOME
Key DOWN ARROW
EndLoop
ClearClipboard
Clipboard 0