Hi and welcome
You are making the same mistake that I see time and time again. You are mixing up the two elements of data capture and final reporting. The two require quite different treatments.

A lot of people start by designing the form that they expect to see as the final report or which at first glance seems the best way of capturing data, and then wonder why it's so difficult to subsequently analyse and summarise or extract information from it. Yours exhibits all those features.

You should always capture data in a simple two dimensional table and worry about reporting information from it afterwards. Without exception doing this you will always be able to easily obtain management information. Rarely is this the case if you start the other way round.
You will also throw open the whole wonderful world of the powerful Pivot table functionality.

After doing that the answer to your requirement would be to use Excel's Filtering functionality

Perhaps post a sample sheet if needed, but be aware that merged cells are to be avoided at all costs


And as you can see, Arvi used a simple multi column table with a row for each event with which you can do what you want afterwards