Delayed Choice Quantum Eraser variation results

if the beam splitter configuration between D1 and D2 was altered so that 75% of the photons from each slit to go to D1 and 25% of the photons from each slit to go to D2?

This behaviour is unphysical from any beam splitter.

Take a beam splitter with two input ports, $rm in_1$ and $rm in_2$, and two output ports, $rm out_1$ and $rm out_2$. Because of conservation, if you impose the requirement that

• each photon entering $rm in_1$ goes out of $rm out_1$ 75% of the time and out of $rm out_2$ 25% of the time,

then it must also be the case that

• each photon entering $rm in_2$ goes out of $rm out_1$ 25% of the time and out of $rm out_2$ 75% of the time.

The reasons for this are technical; they're explained in depth in this previous answer.

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If you were to use such a beam splitter, then you'd get a result halfway between the which-way path (D3/D4) and the quantum-eraser path (D1/D2): you would still see some interference, but with a reduced contrast, and with the distributions moving away from the center: