The best source for information re: your build will come directly from @Sleep_EZ but I’m happy to share my thoughts as well!
Speaking very generally, this should give you the plush feel up top while keeping your spine well supported underneath. Talalay on top helps with comfort and contouring, while the Dunlop layers below will give you the deep support you need for back sleeping.
Going softer with Talalay as the top two layers should help ease pressure on her shoulders and hip. This is a relatively soft build by industry standards. Which Posh and Lavish did she like? I’d be interested to see the layer configuration in the bed she tested.
It was the relax with two inch Talalay topper just don’t have 7k at the moment. But it was the most comfortable mattress I ever laid on. Might make a make shift posh and lavish with sleep ez then buy their topper for the top. The topper alone is like 1300 bucks haha