Hello to all of you !
I found some answers to my problem but the suggested solutions do not fit my particular situation. I am not knowledable enough to succeed in modifying javascripts or plugins so they do what I want. So here is the situation:

I am working with LS 2.06+ Build 160129.
The questions will be displayed on the same page (most probably)
=============================
Question 1 (type = one choice radio button)
How many cats do you own?
o 1 cat
o 2 cats
o 3 cats
....
o 8 cats

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Answer varies from 1 to 8
Lets say the respondent has 3 cats
=============================
Question 2 (type = multiple short text)
What is the name of each cat you own?
Name of cat 1: sultan
Name of cat 2: beeloo
Name of cat 3: pacha

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It is easy to filter the rows with relevance box for each sub-question so the number of rows displayed is equal to the number selected in Question 1. No problem here
For each sub-question I put the following filter in the relevance boxes (8 boxes) : Q01.code > 0, Q01.code >1 ...., Q01.code >7
Essentially, for a given line (lets say 4), it will be displayed if the respondent clicked on radio button 4 or 5 or 6 or 7 or 8
===================================
Question 3 (type = array text or array numbers, etc)
For each cat you own, answer the following questions (about 25 sub-questions):
sultan beeloo pacha
Weight
Age
Sex
Colour
...
Race

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In the X-scale, I can enter all the sub-questions
On the Y-scale, I can list all the cats' names with something like this: {Q02_1.shown}, {Q02_2.shown}, ..... {Q02_8.shown}
Looking at the question I see
Sultan Beeloo Pacha Empty box ...... Empty box
Weight
Age
Sex
Colour
...
Race

---

Unfortunately, there are no relevances or filters for the colums (Y scale).
The way I envision the solution is:

For each of the 8 possible columns (coded 1 to one has to check if : answer to question 1 (number of cats owned) is more than column number - 1
So for Question number of cats owned = 4
Column 1 : displayed if Q1.value > 0 : 4 > 0 : True >>> Displayed
Column 2 : displayed if Q1.value > 0 : 4 > 1 : True >>> Displayed
Column 3 : displayed if Q1.value > 0 : 4 > 2 : True >>> Displayed
Column 4 : displayed if Q1.value > 0 : 4 > 3 : True >>> Displayed
Column 5 : displayed if Q1.value > 0 : 4 > 4 : False >>> Not displayed
Column 6 : displayed if Q1.value > 0 : 4 > 5 : False >>> Not displayed
Column 7 : displayed if Q1.value > 0 : 4 > 6 : False >>> Not displayed
Column 8 : displayed if Q1.value > 0 : 4 > 7 : False >>> Not displayed

---

Now the problem is how can I do this ?
Thanks again for reading all this.

I'm not in a position to test this weekend but you may be able to filter with a hidden multiple-choice question toggled by JavaScript. Try searching the forum for "hidden multiple-choice".

Hello,
Thank you for you reply. I had a look at the 33 responses for hidden multiple choice and its not exactly what I need.
I also tried the plugin of Mr Chenu. This is nice and the demo works with LS 2.06. However, I really don't understand how it works. All I see is the word "LIGNES" or "COLONNES" in array filter. Where is the EM? I display the logic page report but could not find any relevant EM.
As a newbie, I am lost. Can someone who is using the plugin bring me up to date on the use of the plugin?
Thank you again.

Note : It would be so nice to have relevance for columns just like we have for rows in LS 2.06.