Matrix dimension based on multiple slicer selection

Hello Power BI community,

I would like to give the user the possibility to choose in which column the element from dimension table will appear in the matrix. That is why I created three slicers for each position of matrix table. If the user selects BMW from Slicer 1, I expect that this element will appear in the first column of the matrix. The same applies to Slicer 2 and Slicer 3. The user can select any and only one element from each slicer. So applying alphabetical order or any other predefined rule is not possible. I assume I need a UNION of all selected values that I can use as a column dimension in the matrix.

I tried to use calculation groups. I am able to define calculation items that take selected value from each slicer. That works fine, but the calculation item's name (that is shown as the header of column) is static. I also tried to use dynamic textboxes that I positioned over the column headers. However, they don't move with scrollbar on the matrix if we enlarge our example to more than only 3 column (e.g. 10).

Any ideas? Anything is appreaciated.