Thoughts on this container combo?

Dinnerplatedahlias🌸

Bought a few more plants than I needed from garden centre and thinking of potting up an ADESSA Phlox (purple star) and a Pernettya together. Is there a chance the Pernettya could spread and take over the phlox or should these two be ok together? 
Thanks for any advice ☺️

Borderline

Short term it is fine on a container together but bear in mind it is a shrub that will spread and possibly sucker, so unless you are trimming it yearly, they will want to grow. Also, they need neutral to acidic conditions to do well.

Not an issue for your Phlox, but for longterm, I would keep the shrub separate or plant into the ground if you have the right type of soil.

yorkshirerose

Phlox are really not happy in containers. They are more likely to succumb to powdery mildew in a pot than they are planted in the ground.