Measure to select rows based on dynamic conditions

Hi, I'm relatively new to PowerBI so I have been searching for so many ways to do this but none of them seem to fit. 

I would like to find a way using a measure to select rows based on a condition, and on top of it, select all corresponding rows with a matching category. The catch is that the condition is dynamic.

This will probably be easier to illustrate with the below example.

Suppose I have the below dataset, displayed in a table visual:

Suppose I want to select such that Value < 50. 
My requirement is that, for any row that fulfils the condition, I want to
1. Retrieve that row's category

2. Select all other rows with that category

My desired output will be as follows:

I have indicated in red the rows that match the condition. In this example, since those rows are A and C, all rows with categories A and C are selected. 

Currently, the problem I'm facing is that since Measures only work on a row context, there's no way I can select all other rows with the corresponding categories. Currently, the measure I have looks something like this:

Selected =
VAR N = [Parameter Value] // To be selected by WhatIf Parameter Slicer
RETURN SWITCH(TRUE(),
Value < N, "Yes"
)

As you may be able to tell, this can only get me the exact rows that match the value (Only those in red in the table above). I can't figure out a way to get it to work for other rows with the same category. I've looked at this which is essentially what I need, but it only works for a set value, not a variable, so it would not be able to work dynamically. 

I've thought of ways, such as creating another calculated Table or Column to 'store' the 'Bad' Categories (in the case of this example, A and C) so I can reference to it when selecting. However I have read that calculated Tables are not dynamic and needs to be refreshed manually, so that may not work in my case. Additionally, I can't really utilise Power Query or make direct changes to my dataset as the automated data-uploading process is pretty much already set in stone and my supervisor has requested that direct changes to the dataset be minimised. If there is a way I can do it in just measures, that would be great. 

This is probably the simplest way I can put in words my current problem. If it is truly possible to do the above using measures, it would be a great breakthrough in my work. My background is in programming and not so much in querying language, so learning to navigate DAX has been a challenge. I will be very grateful if anyone can help me with this issue, and will gladly provide more information if needed. Thank you!