Chances of regularising an apartment in Brussels

Hello Forum,

I am living in a ''maison de maitre" in Brussels capital region. It is more like a penthouse which has been split into three apartments  and registered by a notary way back 1992. This registration, clearly mentions the following:

-lot1, l'appartement du rez-de-chaussée. comprennent do relavent trois cent nonante-deux/millieme(392/1000)
-lot2, l'appartement du rpremeire etage. comprennent do (412/1000)
-l'appartement du deuxième etage, comprennent do relavent trois cent nonante-deux/millieme(196/1000)

I own both ground floor and first floor apartment, with a quote part of (392/1000) + (412/1000)
This second apartment has come for a force sale through notary now with following details"

But commune has written a letter to the notary stating that:

AS per this document, the second floor (deuxieme stage) doesn't exist . Here is the commune response:

- If I buy this apartment on force sale, What are the chances that I would be able to regularise this apartment?

Notary says, although commune was not aware of the third apartment in II floor,  the 'acts de base' showing the split of three apartments  was done in 1992.    The chance of regularising the third apartment in second floor, are high -  is this true?