The challenge with the case shown is the position of the ERA attachments have been positioned about 20 degrees off angle from the plane of occlusion. This will lead to problems inserting the case, prohibit the attachments from functioning the way they were designed to and result in causing the attachments to wear out prematurely throughout the life of the bridge. This is a situation that we are often presented with as your removable partner.
Our recommendation anytime you are doing a combination case would be to have your C&B lab articulate the case, wax-up the substructure and have it sent to us to evaluate the attachment position prior to casting. At this point, any necessary corrections can be addressed without having to remake the entire bridge.
Remember to tap into our expertise as often as you need to. It will save you time, money and frustration in the end!