You're the one who has to live with it so it's absolutely your prerogative.
However, you're pushing water uphill, Yew is an exceptionally warm toned timber, famous for it's orange/pink colour. Oak on the other hand is much cooler toned, not as cool toned as say Walnut but certainly cooler than average with subtle green and straw tones. Personally I think you'll end up with an unconvincing, weird hybrid.
The second issue is that Oak is open grained but Yew is close grained, all the colouring in the world won't change this.
And finally, quarter sawn Oak has really distinctive flashes of medullary rays, Yew doesn't have medullary rays. So basically you're trying to match two timbers that are inherently different. As I said, your house so your call, but my advice would be to celebrate the difference and not try and force a match that nature never intended.