Bespoke Cutter And Tailor

Hi.
Hendrick here. I am partner in a design studio that was founded over twenty years ago. We offer forecasting and design services mainly for wholesellers and commercial brands. Over the years we have seen tremendous change in businesses with them sourcing from ever lower wage countries.
I was ”born in the industry”; my dad was an accomplished master tailor who became partner in a garment factory. Clearly, I had a great view of the near total demise of the garment industrie in Europe. Before my dat would let me go to fashion school, he decided I “must learn something about garment making”. Hence, I was sent to technical colege and got an associates in garment manufacturing. Mind you; the sewing I did there is best described as “very experimental dressmaking”. The pattern making training, however, was excellent; we got the full rundschau method rubbed in. Otter than some modifications I didn’t do any  sewing for years. After all  these years in fast fashion, however, my fingers  started itching, I bought avfew gorgeous old sewing machines an slowly I am taking off! For now, all this is “therapeutical”. I am happy to to be here, taking a bow to all you lovers of the arts, not in the least place to the highly inspiring Rory Duffy...

Thanks for your contributions, greets, Hendrick

M is the centre point between G-G1.

you just cut a facing on. Means 4 cm width and length as then zipper should be. Iron Interface to the facing - on left and right side of the trousers . Mark with a seam (dark color)  the Center front (left and right). Iron the left side into the inner side . The right side stay as is. Now you can pin the trouser close when fitting the sloper. Need no Zipp.
Little shortness at back crotch point: the back crotch curve is not long enough - you altered that already. But I think too much. And it may be because of your thigh circ that they pull the fabric in. So it may be you can alter the form of the inseam a bit.
lg
posaune
ah and front crotch: I think the form is of the curve is not okay.

Now I am even more confused...

Though now I understand for the sloper need to ignore the fly until the final, so how is a fly added to the final then?

I didn't notice the reply until getting on to draft a new post on Rundschu Cutting System.

Knew forgot something... posaune, you are correct, the right hip is higher than the left by about 3/8 inches, good eye.

Photos now are wonderfull.
If you did the alteration to  the 1. sloper, " seems the fabric has stretched with wearing", maybe it has stretched more, because now it is too long at the back and too wide. (I think that fabric is to weak for a pants muslin). And it would stretch were the bias is -  that is mostly at the center back seam. Did you attach the waist band new?
Looking the side view I would say the front is too tight. See that from hip point up to waist band the side seam goes slightly so / . Means let out the front side seam, till it runs straight. This will effect the back (waist) naturally.
You have not done lines where your hip is (horizontal) in front and back - so I have to guess. But I think your pants is now out of balance - the back is too long. The added 2.5 cm may have been a bit too much.
The right hip is higher than the left. To prove this you have to measure from floor up to your waist.
I'll attach a link where you maybe can read some good stuff about fitting a pants (it is for woman but the fitting problems are the same)
https://closetcasepatterns.com/pants-fitting-adjustments-best-tips-for-pants-fitting/
lg
posaune