Question about fabric and lining

I want to flatline (ie. treat fashion fabric and lining as one) my skirt for my 1895 ensemble. I'm using a wool suiting and planning on lining with a plain, lightweight cotton. I'm using this pattern. My question is: do you think it's alright to flatline the wool or do you think the bias will make it wonky after I've left it to hang before hemming? It's very bias-y and I'm worried that the wool will stretch more than the cotton.