Good Morning Sebastian.
Researching for this does not reveal a possible customization for this.
And then/thus please check on the somewhat 'formal statement' below.
What you want to accomplish then, as this now appears, is more than desinged in the software sofar.
And in general, for situations like this, where a user asks for a change of behaviour of the current release of the product, I can propose to add an Idea in the Communities.
So, as to this case, we then encourage you to open an Idea in the CA Service Catalog Community.
To get your Idea voted for and reviewed by us there after.
For us to see whether it is possible to get this functionality implemented in a future release of the product.
Thanks in advance for your efforts on this and kind regards, Louis.