WARNING: You may consider this picture NSFW! Nothing actually indecent, but quite revealing.

I have a problem making a separate bottom version of these metallic male shorts by Newsea. The Sim on the right is wearing the original full body adult male version by Newsea.
The two on the left (one teen, one adult) are wearing separate bottom versions of them that I've made (or tried to make) myself. For the purpose of illustrating the problem, I've paired them with nude tops. The problem is that brown band above the waistband of the shorts. I do conversions like this all the time, and I've not seen this problem before. To make the separates I use the Full Invisible Clothe Set by Drachenfels ("Drachis" in tooltips) on Sexy Sims. This gives me access to all the Maxis nude meshes. I used the textures from the Newsea shorts with them. This method has worked well for me for a lot of other skin-tight clothing.

Two possible clues to what is going on occur to me:
1) The Newsea original uses a bumpmap, but the Drachenfels nude bottom doesn't have one. I've seen a couple of tutorials on adding a bumpmap to an outfit that doesn't have one, so I think I should be able to do this, especially as the Drachenfels texture uses a Maxis mesh.
2) The Newsea shorts don't use the original Maxis male full body mesh, but use a slightly slimmer mesh of their own. I'm not sure I'm able to deal with this myself - I suppose I'd have to edit the Newsea full body mesh in Milkshape to make a bottom mesh out of it, and I've never done anything like that.

Can anyone suggest a way for me to get rid of these ugly brown bands? I recall seeing a tutorial somewhere on MTS about removing the black line at the waist that you sometimes get when using separates, and I think this may a related issue, but I can't find that tutorial now when I look for it.

I suppose this properly belongs in the creation sections, but I feel a bit lost there. I don't really think of myself as a Body Shop creator -- more of just a tweaker! If anybody can point me to tutorials that might help, I'd be most grateful.

TBH I stopped using Familyfunds a long time ago, it's too buggy. I use Pescado's Money Order and just get them to send money to a random townie if I want it to go nowhere, and Cyjon's Loan Jar (and then just delete the jar if you don't want them to pay it back) to add money.

I wasn't making the funds negative, I was subtracting funds. Regardless, it just doesn't work at all with the Peterson household, I can't add, subtract or set a fixed amount.

Your alpha isn't lined up with the texture. It will be because you aren't using the same mesh as the original underwear. I'd imagine that just above the part of the texture that's supposed to show is a gold bucketfill and that's showing up because the alpha is set too high. The bottoms of the undies are also cut off because of this. Move your alpha down.

Is there a way to set a sim as the Mr. Big/Diva or is it like an NPC generation thing?