VBA Compare dynamic H&I, add value from H to I if not present in I to the end of the list

[Xiggie]

Hello!

I am struggling with comparing two columns and adding missing values from H&I to J&K, while keeping the rest of my macro intact.
So far I have a macro which checks if J&K are empty, and if they are empty it adds values from H&I to them, see below:

Sub Total()
Application.ScreenUpdating = False
Dim c  As Range
    For Each c In Range("J23:J32" & Cells(Rows.Count, "J").End(xlUp).Row)
        If c.Value = "" Then c.Value = c.Offset(, -2).Value
    Next
    For Each c In Range("K23:K32" & Cells(Rows.Count, "K").End(xlUp).Row)
    If c.Value = "" Then c.Value = c.Offset(, -2).Value
    Next
Application.ScreenUpdating = True
End Sub

I want to add two additional conditions:

1. If J is not blank, then compare all of the values from H with values from J and add missing values to J to the end of the list, wherever it might be, and put values from I from to K.

So, for example, if H30 value is missing from column J, I want H30 and I30 to be added to J&K column.

1. If J is not blank, then compare all of the values from H with values from J, and if the values match, then SUM the value from column I with value from column K.

For example, if H30 is present anywhere in column J, I want to sum I30 with K30.

Columns A:G are irrelevant under the circumstances.

Clear macro is as follows:

Sub ClearContents()
Range("J23", "K53").ClearContents
End Sub

Thank you very much in advance!!

Cheers