If they aren't blending, you aren't going to hide them (other than leaving them in the band hall). First thing with oboes is always to get help with reeds.

One issue - and looking at your setup this may be a problem - is that the oboe resonates outside the face, as opposed to the other reeds that resonate inside. Being next to those trumpets they may not be able to hear themselves, and if you can't hear you can't match. I know that when I am playing in passages where it is difficult to hear, I have to first trust my reed and experience on my instrument and its tendencies (not going to happen with MS NV oboes...), and second listen carefully for sound 'feedback' that tells me I may not be matching (or someone isn't matching me).

I am guessing you are not playing things with divided oboe parts. Split them up. Have one or two play exposed or problematic passages and alternate. Only use all three in louder tutti passages. We do this in a group I play in on the rare occasion we get a single part. No reason for all three of us to play all the time on that part. It will be easier for them to match.

With oboes it is like the old military adage of 'three on a match'. In the dark, by the time the third soldier on a match lights his cigarette, somebody gets shot. Now, before someone cries that I said oboe players should be shot, I just mean with three you open yourself up to some potential bad stuff.