[jazzbyrd]

Would it be a problem growing some sweet peas in and amongst eating peas or should I keep them apart?
 

[Trillium]

Best to keep them apart as one could easily swamp out the other depending on variety. You might also not be able to easily see the sweetpeas, which would be a true waste. If you're short on space, plant the sweetpeas at just one end of the pea row.

[azubah]

I would keep them apart as the eating pea plants do not last long.
I pick the last few peas by pulling up the plants, and this would shorten the life of the sweet peas as they will all be tangled up together.
There is also the risk that you could get a few sweet pea seeds mixed up with the eating ones, though they are smaller and harder.
Also, picking peas is hard work and you will miss more if they are mixed up with sweet peas.
I intend to grow sweet peas with my runner beans, which does not seem cause any problems.

[Yorkie]

Good points azubah!