I agree with Jiffymouse's reasoning for planting the Sansevieria with the Croton or D.marginata. However, I also advise against companion planting the Croton and D. marginata as they also have different light and water requirements. I have tried planting the two together in the same pot with dismal results.
Crotons do best in direct sunlight and don't like their soil to dry out much between waterings.
D. marginata thrive in bright indirect light and needs to dry out between thorough waterings, though not as much as Sansevierias..
If you are willing to keep the Sansevieria and D. Marginata in their individual pots, you can plant
them together in a third, larger ornamental pot. That way each plant
can be watered according to its individual requirements. Sanseveria is touted as a good low-light plant
because it can survive in low light but it thrives in bright indirect light so might work well with D. marginata. One of mine has tripled in size in three months, located in a west window.
For the best success companion planting, choose plants
with similar care requirements.
However you choose, please post pictures. It sounds like an interesting project.