We need to include the manufacturer part because we need to appear as the "manufacturer" in the certificate.
This is just a terminology. "Manufacturer" on the certificate relates to your regulatory status. You could be the regulatory manufacturer without doing any actual manufacturing, and it says quite little about your specific regulatory obligations.
Today, the OEM told me that there is a fastest way for us to achieve ISO and it is less complex and it is applying as a ODM. Original Design Manufacturer. Do you know anything about it?
No, I don't. Perhaps your OEM was referring to what we are already discussing. It sounds like your OEM is referring not only to ISO 13485 certification, but to EC clearance (CE marking). There is no "faster", "less complex" way to get ISO 13485 certification than to scpoe and apply a QMS that is in alignment with what the organization actually does (which excludes manufacturing in your case).
After reading some information online, it seems to me that every NB will requiere different things. For example, some of them waive the audit to the OEM. Some others requires only a technical file so does this means it would be better for me to look for a NB that do not requires too much from my business?. For example, if the audit on OEM are waived it means we will save money by no having the OEM audited. Others people recommend me to use the same OEM NB since they have their information on file but this NB has told us they will audit the OEM. So at this point not sure what to do.
I apologize upfront if what I'm about to write will sound like self promotion. This is not my intention. I don't even know where your organization is located so there's a good chance that I'm not relevant to you (I believe that the best is to have the consultant come on site at least once or twice for a QMS implementation).
You sound confused and lacking necessary understanding of how the relevant regulatory systems work, what the various elements mean etc. Reading online can be a great way to learn, but let me warn you that to get a good understanding this way you will have to spend many days (as in weeks and months) reading. Plus, your potential OEM is not the best source for regulatory advice. Remember, they are a stakeholder and their interests might not coincide with yours. I think you really need a good consultant by your side - someone whom you trust, because there will be situations where that person will tell you "this is in your best interest" and it will be, even though it will seem to you that there is "a better way". In regulatory affairs, sometimes the "longer" and "more expensive" way turns out to actually be the quicker and cheaper.
Specifically, it's important you understand that what you refer to as "ISO" is actually more than just ISO 13485 certification. For ISO 13485 certification you don't necessarily need a NB - any ISO 13485 certifying body (CB) would do. Mentioning a NB tells me that you're actually after an EC certificate, which is required for CE marking of devices in classes higher than plain class I. Until now you have asked about ISO 13485 certification, and my answers to you were in that context. EC certification involves additional nuances.
it's true that different NBs require different things, but I believe that in this case it looks "different" to you simply because you lack the background to understand what they are talking about. There is an OBL track for CE marking, based on an existing clearance held by the "real" manufacturer (the OEM). This track is normally quicker and easier, however it only works if the OBL hires the same NB as the OEM. In that arrangement, the OEM is being on-site audited by the NB anyway, to get their own EC certification, regardless of the OBL; so there's no need for additional auditing just because they contracted with the OBL. Whether the OBL certification involves on-site audit of the OBL is up to the NB, but I think most of them are likely to audit at some level.
I don't think it would make practical sense for you to try and become a regulatory specialist for this. Instead, I recommend that you find someone knowledgeable that you really trust (and is really committed to walking you through) and follow their advice, rather than collecting bits and pieces from various sources. I apologize if it comes across as offensive, it's not my intention and I really believe this is in your best interest.
Good luck,
Ronen.