Toy to go into pussy while having anal sex

My girlfriend likes DP.

I bought her a butt plug to wear while I'm in her pussy and she likes it.

She also likes to have a dildo in her pussy while having anal sex too and it needs to be pretty big.

The problem is that the dildos slide out of the pussy and it's awkward to keep shoving them back in while I'm in her ass, because usually it's doggy style.

I had some thoughts about making some sort of a harness to keep the dildo in her pussy, while keeping the ass open for dick... but that seems too elaborate and complex for my ropework skills. On the other hand there's scotch tape... lol

How would you do it? do they make toys for staying in the pussy while she's getting it in the ass?

Get a strap-on.

I can't think of anything you can do to her to get this, I'm not familiar with some kind of harness she could wear too keep it in (but I am sure there is one).

However, you could wear something like this http://www.lovehoney.co.uk/product.cfm?p=11056

I think how it works is pretty self explanatory.

Though they're a bit pricy, we've been very happy with the Liberator products we've purchased.

Perhaps something like this would work https://www.liberator.com/wing.html

My former girlfriend and I compromised. She lied on her side with knees pulled up to her chest. First I slowly filled her ass with big anal beads. Then I used a vibrator in her pussy, very slowly moving it in and out until she got near orgasm. When she began to come, I pulled the beads out of her anus slowly.

I don't know why the obvious has escaped everyone. . . .

Get a good sized butt plug (solely for her vaginal use) have her insert it and fuck her ass. She should be able to hold it in with her vaginal muscles.

If necessary you can cut off one side of the flange of the butt plug, or you can cut off the entire flange or you can use a dildo and just stuff the whole thing in. It's not as if it will get lost in there. It can only go so far.

If you are doing her doggy style where are her hands ? Surely she can work whatever it is you are using in her to her liking in that position . I know my hand would be on my clit and I would be gripping ( dildo, vibrator ) with my vaginal muscles . Practice, practice, practice lol.

You can always turn a strapon inside out and can wear it in either place.