Eidolon Bugged or Confused by Natural Attacks?

[Jamz]

OK, so I'm building out my Unchained Summoner to 9th, Angel subtype.

Currently she has 3 Slam attacks, 2d6+6 (str*1.5, bonus of 4 = 6). Now, if I take Wing Buffet, it drops the Slams to 2d6+4 (str*1 vs str*1.5) so looking it over, I'm trying to figure out Natural Attacks...

So, why is this? Or rather, why does she get 1.5 str with 3 slams? Primary attacks are full BAB with full str. Now, there is this line, "If a creature has only one type of attack, but has multiple attacks per round, that attack is treated as a primary attack, regardless of its type.", which ok she has only 1 type (Slam), but a primary attack is still full bab and full str, not 1.5 str.


So we come to this line, "If a creature has only one natural attack, it is always made using the creature’s full base attack bonus and adds 1-1/2 times the creature’s Strength bonus on damage rolls."

Does "one natural attack" mean one "type" of natural attack, eg Slam, or 1 actual attack, ie 1 Slam attack?

So it seems to me either, A. Taking Wing Buffet shouldn't change the Slam Attacks and they are still *1.5 str... or more likely B. After adding a second (or third) Slam attack, the damage should drop to str*1 vs str*1.5?

Ready to be schooled!