I am building exterior shutters with (1-inch thick) Azek PVC for durability. I will soon paint them with Sherwin Williams Duration exterior acrylic (dark color with Vinyl Safe tehcnology to minimize expansion/contraction); they say Azek doesn't need priming. I have decided to attach some small appliques (about 2-3 inches wide/long) which repeat the same motives elsewhere in the house and will brign visual consistency). For a number of reasons, the appliques will be made or (3/8" or 1/2" thick) redwood, with oil primer and the same Duration topcoat. Given how the project is going, I will likely paint the shutters, then paint the appliques, and then attach them to the shutters.

Question: does the potential difference in expansion/contraction rates between Azek and redwood matter? What should I do to attach the appliques -- glue or screws (or both)? If gleu, is it OK to attach both surfaces after painting, or is it better to attach them before painting (but, of course, after priming the appliques).

My intuition tells me that, given they are small, it is OK to just paint both surfaces before attachment, that glue would suffice, and that the expansion/contraction shouldn't be a problem, given the size of the appliques. But I just want to double-check. Thanks