I have a problem that I hope you can help me with.

I have 2 lists with categories that I wish to present in a different way (see image). Columns B C are my input and columns E F are my desired output. the content of B C will be dynamic and so I hope to find formulas that can help me keep the E F columns updated.

column B includes groups and column C includes subitems every list of subitems in column F should start with a subitem that is equal to the group name If there is a group in column B with no subitem in column C, the subitems will just present the group name and then move on (like the "travel" example).