Louis, I agree with Julie. The short answer is yes, you can create a profile for anyone, whether related to you or not, and you can add notes to existing profiles of family members, but the right approach would be to do some research first and see if you can find some records that prove or disprove your suspicion. It is not all that unusual to find multiple people with the same name, at the same time, in the same general area, particularly if it is a common name. And there are generally records available in the era of 150 years ago, so you probably don't need to guess at it, just take a little time to search the available data.