Regular mesh - how not to disturb mesh in adjecent SAR

Hello,

I am modeling arch/vault bridge and currently working on achevieng good, regular mesh.

I menaged to get regular mesh in masonry (orange) and filling (blue) but now i would like to add additional elements above them (grey area)


Could you please help me?
I would like my masonry and filling areas to be master and grey area to be slave
Grey area always disrupts adjectent area, even if they stay regular it causes them to subdivide

//edit: Can you turn off SLN subdivision adapatation to adjecent mesh?
obraz
I want my SLN to define mesh not the other way around