Can't figure out how to make a grammar LL(1)
For context-free grammar to be LL(1), these two requirements have to be met for its every rule $ A \rightarrow \alpha |  \beta$:


$  FIRST(\alpha)  \cap FIRST(\beta) = \emptyset$
$ \epsilon \in FIRST(\alpha) \implies FOLLOW(A) \cap FIRST(\beta) = \emptyset$



  Does it make sense to look at FIRST+ in terms of each production that has the same left hand side? 


No, as you can see, to decide if grammar fits those rules above, we have to calculate $FIRST$ function for the right-hand sides of the grammar's rules, not for the left sides.

For your grammar, we get these results:

$A: FIRST(Ba) = \{c,d\},\space FOLLOW(A) = \{\epsilon\}$

$B: FIRST(dabB') = \{d\},\space FIRST(cBbB') = \{c\}, \space FOLLOW(B)=\{a,b\}$

$B': FIRST(acbB') = \{a\},\space FIRST(\epsilon) = \{\epsilon\},\space FOLLOW(B')=\{a\}$

As you can see, there is a $FIRST/FOLOW$ conflict (violated second requirement from above) in $B'$. You can read here about how to solve this.