Understanding a TCG card effect 2 - が indicating property/condition?

Question

This is a bit of a follow-up question to the similarly-named Understanding a TCG card effect; I've got two more cards using the same grammar point that I'm having trouble understanding:(1)

1. キャラカードを1枚選び、捨札置場に置く。あなたの場にあるキャラカードを1枚選び、そのカードが所属する部隊を捨札置場に置く。
2. 使用キャラカードが所属する部隊をスタンバイゾーンに移動し行動可能にする。

The bits I'm looking at specifically are bolded. In my previous question, @ki said that the が there was acting to indicate the condition/property of what was marked with が。Is that still the case here?

For the first, I'm having trouble telling whether just a Character card or the entire Unit it's assigned to is discarded. For the second, it reads like you need to move the Unit the Character card belongs to back to the Standby Zone, which doesn't make sense according to the rules as I've read them; you're supposed to leave the Unit in the Standby Zone in the first place. (See the footnote.)

What function is the が in those bolded sections performing? How should these card effects be read?

(1) Some more context for these cards: they're both skill cards being used by Character cards. Character cards (キャラカード) group together to form Units (部隊). These Units sit in the Standby zone in an active state; when you use a skill card, you take one Character card from the appropriate Unit and move the Character card to the Action Zone. The Unit flips orientation to show that it's now in an inactive state (can't be used w/ other cards this turn.)

Answer 1

What function is the が in those bolded sections performing?

In both sentence, が is the plain subject marker that marks the subject of 所属する, which modifies 部隊 as a relative clause. It appears that you have parsed these sentences correctly. The object of (捨札置場に)置く is clearly 部隊 in Sentence 1, and the object of (スタンバイゾーンに)移動する is also 部隊 in Sentence 2.

あなたの場にあるキャラカードを1枚選び、そのカードが所属する部隊を捨札置場に置く。
Pick one character card that is in your 場, and place the 部隊 which that card belongs to into the 捨札置場.

使用キャラカードが所属する部隊をスタンバイゾーンに移動し行動可能にする。
Move the 部隊 which the character card (using this skill) belongs to into the スタンバイゾーン and make it (=部隊) actionable.

So these sentence are saying 部隊 is something that can go into the 捨札置場 and the スタンバイゾーン. You're saying this won't happen, but I think this is the only plausible interpretation.

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By the way, I think が in 戦闘力が使用キャラカードの戦闘力以下のキャラカード can be explained as a plain subject marker in a relative clause. This noun phrase is constructed from the following base "double-subject" sentence.

このキャラカードは戦闘力が使用キャラカードの戦闘力以下だ。
As for this character card, the power is less than or equal to the power of the character using this skill.

(Note that 以下 works like a no-adjective, and the attributive form of だ is の, e.g., この本は表紙が緑色だ → 表紙が緑色の本.)