Thank you very much for the clarification

Then, I understand the following:
1. if the OEM company has a product with CE marck (for instance CE 130)and PLM company sign agreement for the identical product, PLM now is the legal manufacturing and keep the CE mark from OEM (CE 130), does not it?
Question:
1. how OEM company can obtain certificate of Directive 93/42/EEC, if it only designs and manufactures, OEM company do not labels the product, PLM (private label manufacturing) states the labeling?? please explain me.
2. if OEM company would not have the certificate of 93/42/EEC, PLM company will request this certificate??
3. considering the case that OEM company has own CE mark, when it decides to make some changes in the product, it have to inform to notified body??? the notified body
considering the magnitude of the changes can be considered that the product needs certify again?
4. please tell me what is he meaning of PMS??
Thank you very much in advance