Thank you for detailed guide, appreciate it! I forgot about my Origin client, however in 'My Games' tab there's only one game - Inquisition - that I own on PC. The other two games are on my xbox 360, digital purchase. Isn't the Origin client supposed to be for PC games only?
I can clearly see both items on your list, and here's mine screen:
http://imageshack.co...5911/nClDpZ.jpg
http://imageshack.co...6325/FXIDSG.jpg
You can link your XBox/PSN accounts to the Origin client
https://help.ea.com/...d-and-gamertag/
But, you have to have the same email address for all the accounts. Not sure if that will work, as all my EA/Bioware games are the PC versions (but for some reasons, i could get everything for consoles, too, as you could see in the screenies) 
And, no. I did not have pre-ordered Dead Space 2, but i did have my saves for DA:O and ME2.
Blood Dragon Armor was supposed to unlock if you owned either DA:O or ME2, but never unlocked until now. Ser Isaac was granted only to people that had pre-ordered Dead Space 2 (something that i did not do, as i've got the Dead Space 2 years after release). On PC, you can add the items without problems, and even without owning DA:O, Mass Effect 2 or Dead Space (i have friends that own DA2 and DA:I, but not DA:O or any other possible required games) and they still were able to get them.
Worth a try with account linking, maybe you can do something with that. As a final resort, you could probably ask support to add them, seeing that they are given free.