Let's simplify the expression step by step:

First, we need to simplify the two main parts of the expression:

1. \(7/8 - 5/2 + 4/7\)
2. \(-3/7 + 1 - 13/8\)

### Step 1: Simplifying \(7/8 - 5/2 + 4/7\)

First, convert \(5/2\) to an equivalent fraction with a common denominator.

The least common multiple of 8 and 7 is 56.

\[
5/2 = (5 \times 28)/(2 \times 28) = 140/56
\]
\[
7/8 = (7 \times 7)/(8 \times 7) = 49/56
\]
\[
4/7 = (4 \times 8)/(7 \times 8) = 32/56
\]

Now, combine these:

\[
49/56 - 140/56 + 32/56 = (49 - 140 + 32)/56 = -59/56
\]

### Step 2: Simplifying \(-3/7 + 1 - 13/8\)

Convert 1 to have a common denominator with \(-3/7\) and \(-13/8\):

\[
1 = 8/8
\]

Now we convert everything to have a common denominator of 56:

\[
-3/7 = -24/56
\]
\[
8/8 = 56/56
\]
\[
-13/8 = -91/56
\]

Now combine these:

\[
-24/56 + 56/56 - 91/56 = (-24 + 56 - 91)/56 = -59/56
\]

### Step 3: Substitute back into the main expression

Now we substitute back into the main expression:

\[
(-59/56) - (-59/56)(-59/56)
\]

### Step 4: Calculate \((-59/56)(-59/56)\)

\[
(-59/56)(-59/56) = (59/56)^2 = 3481/3136
\]

### Step 5: Combine the terms

Now substitute this back in:

\[
-59/56 - 3481/3136
\]

Next, we need a common denominator. The least common multiple of 56 and 3136 is 3136.

Converting \(-59/56\) to a denominator of 3136:

\[
-59/56 = -59 \times 56 / (56 \times 56) = -3304/3136
\]

Now combine:

\[
-3304/3136 - 3481/3136 = (-3304 - 3481) / 3136 = -6185/3136
\]

Thus, the final result is:

\[
\boxed{-\frac{6185}{3136}}
\]