Ann, after looking at the F-435 profile again, I see that you have a father already attached. However, I don't know his ID since his profile appears to be Red locked.
Could you post the WikiTree ID for your father's profile - I mean the profile that is currently attached as your father? You may have attached a different profile as your father, which is why you can't attach F-436 for now. If so, you will need to detach that profile before you can attach the correct profile.
Also, I had presumed that the profiles in question were F-435 and F-436, since those were the only ones that were in your contributions log when I posted my answer. If you are trying to attach different profiles, post their ID's here.
addition to post
After looking at F-436, I see that a child IS attached (I just can't determine that it is F-435 because of F-436's Red lock). If you have straightened out the child-parent link, Ann, let us know!
Finally, NO, you do NOT want to merge those profiles!!