im not sure what you are trying to do are you adding a new key or trying to re-sync a programmed one

 I did a 2010 ford escape in January, Adding keys did not work, so I went to erase all keys and re-register all keys and that worked.  Search this forum in USA, I had this problem and EDE65 helped me

if no keys present you need 2 keys to program,if you have 1 key programmed and just want another programmed then use program additional key.no master key is required with ford(u.s) at least not sure how euro works.

          All the info you already got is pretty much right. Any programmed key meaning car will start and run can be used to program additional key. If you don't have a programmed key then you'll need to do parameter reset first before going ahead with all keys lost or whatever maxisys calls no available keys. Note about your statement of key restriction there is a data pid  that can be changed in PATS with access I think they call it spare key "enabled" that limits the amount of key programming done my best remembrance is 4-8 keys if it's "disabled". Go ahead and enable then no limits on key programming. Parameter reset is going to wipe whatever box that PATS is stored IE:PCM,Instrument cluster or dedicated security module then compatible key will program.

 From what I recall ,(not sure it still applies on newer Fords) providing the max allowable # of programmed keys has not been reached yet,  If you have 2 programmed  PATS keys with you that start the car and have a newly cut correct PATS key that has not been programmed yet. You do not need a scanner and have to wait 10 minutes to gain security access in order to add an additional key you want  programmed. You take the 2 programmed keys and insert in the ignition turn the key on, engine off  ,till the theft light goes out , then within 2 seconds turn off ignition, remove the key and install the 2nd programmed key ,turn key on engine off,  wait till the theft light goes out , then within 2 seconds install the un-programmed  key  and turn key on and wait till the theft light goes out and the car should then start and the 3rd key has been added.

                    Could be right but best I can tell from post at most he's got 1 key that starts the car. I personally only had to either program another key put in a used PCM which requires a reset since it's married to the old car or customer lost all of them for some reason. Few new PCM's that I put in couple were fleet vehicles that don't use PATS IE:tow trucks,police vehicles. Probably best to check SI information depending on how many working keys 912 guy has. Parameter reset  and erase and program keys is always an option but not always necessary. My biggest concern from post is that spare key programming might not be enabled since customer talked about key limitation for some reason. the only time I did a third and fourth key was with used PCM replacement so I was starting over anyhow just added more.

             An unknown by me supplement to what I've already said going by what I remember in a post here using IDS weren't allowed  past 2010 to do Pats???? Recently used FMP with J2534 and from what I could tell on motor-craft service only stated starting in 2013 PATS not allowed without security professional ID so that's an option it seems and Autel never done it so won't comment.

 same here in the UK 2010> you have to be hooked into the main server but now ford also want security id (and now only allowing ford dealers to have it) even if you have a license and a genuine ids tool.

and no master key here either that stopped in 2001.