DI AwayChaingrab on DI away works, but is technically speaking port dependent. If sheik's port number is greater than the opponent's (4 being the greatest) then she has a true CG on peach which requires you to be frame perfect. I am not sure how long the CG goes, but I'd estimate 20-30%. If you are the lower port number peach has 1 frame to escape.
If she times her DJ correctly she'll jump out, and if she buffers a float she can punish your whiffed grab with fair-->combo.
Of course this also means she's at risk of losing her DJ if you opt for something besides regrab, and slightly delay it to catch her jump.
I'm fairly sure dash attack doesn't combo on DI away, but again, it forces them to jump to avoid it. In practice I've had success with it, but peach players don't seem to know the counter strats out of dthrow very well.
Finally, you can always go for SH or FH fair. FH fair can be good, especially if you have some charge of needles; this is because after the fair hits peach, she is directly at the 45 degree angle below you. This allows you to pressure with falling needles or falling fair/nair. If you go for the SH, your goal should be to auto cancel as soon as possible and go for a mixup afterwards. Depending on her DI, you can go for an immediate grab with high likelihood of success (if she doesn't go into the ground immediately, but also isn't high enough to mash nair out). Otherwise you can DD bait, ftilt, or set up more SH pressure.
I shortly explain usage for ftilt/nair on slight DI away that is relevant for this DI as well, so reference that.
Slight DI awayOn slight DI away ftilt isn't that bad, but it's not that great either. You can always go for the regrab and just ASDI down in case of her mashing nair out, but again if she acutally buffers float or DJs out then you'll get punished.
Dash SH upair does work, and while it won't true combo into anything it has its benefits. You can uptilt afterwards and it'll always hit her before she can jump/float out, though she can trade nair with this. More and more I'm realizing sheik has a lot of *almost* real combos in general, and I think option selecting an ASDI down with c stick at low % actually leads to great stuff. You can SH upair, auto cancel, uptilt then ASDI down; if she nairs it will trade with your uptilt and she'll be in normal stun, while you'll be able to move almost instantly because of the ASDI. Of course you can also just wait below her, DD grab or shieldgrab the nair, or even just crouch and wait/react (then throw out a move, react to her jumping, etc).
On even slighter DI, walk uptilt should combo, or at least hit her before a nair can startup. Again, the closer she is to you, the more viable ftilt is as an option. This includes being a decent option on DI behind. In general ftilt/nair can both be used for a similar purpose: if you can't true combo her, both are likely to put her high enough in the air to either be in an awkward position or land on a platform. This usage of ftilt/nair is also viable on full DI away.