Room with glass windows as a walls.

I don’t mean to aggravate you @surfmuz but you can see people are trying to help but they are lacking basic info to understand what you need. Such as what matters to your daughter, the floorplan you later described, her interior design preferences, budget, etc. For instance, in my reading, you are trying to help her but she is...

somewhere between indifferent to not seeing this as a priority?

How do you help someone who is happy/fine with the status quo? I have helped (tried to help) my kids, friends and neighbors and ran into the same issue, people need to want to be helped for it to work.

Use a pair of Magneplanars or similar dipoles which have less interaction with the sidewalls the room. That will at least mitigate reflection problems.

Agree with the Maggie's having less sidewall reflection problems. I removed my acoustic panel for the first reflection when I had the LRS+ in my old office. I got a pair of Mini Maggies yesterday for this same reason but for an even smaller room than the LRS+.

My DSP solution with the convolution filters is a one and one solution without any visible cosmetic changes to the apartment.

@OP you can generate convolution filters for your daughter’s room yourself with REW (open source software, free) and the aforementioned $100 mic.

Then, instead of expensive roon or JRiver you can run Daphile (Linux-based, open source, free) on the same suitably minimally configured PC you would need to run roon on anyway, load your convolution filters in Daphile, and voilà.

Not sure about the cost of ROON these days but I bought a lifetime subscription 10 years ago for $450

It’s $830 right now.

Good advice from @yyzsantabarbara as usual.

$830 for Roon is one of the best things a hard core audiophile who is also a music lover can buy.  I did.   The DSP using convolution filters and all the rest can be best thought of as a priceless bonus feature!!!

I use multiple third party convolution filters for specific headphone models and several I created myself with REW for various rooms in my house where I listen.

@grislybutter 

they are lacking basic info to understand what you need.

What I need is clearly stated in my post, isn’t it. 
I was asking if anybody had experienced setting up a system in such conditions.