Q: When White Len pulled Arcueid into her world, there were descriptions of the support from Gaia being cut off, can all users of Reality Marble do that?
A: That's in the story of Melty Blood Re-Act. Reality Marble is not the alteration of things or events, but overwriting (covering). Thus, what White Len said is possible. It is like overwriting existing field effect with another one. However, even if the field is changed, whether Arcueid's support would be severed depends on "what power is used to construct the boundary field". If an alien deployed the Reality Marble, then Arcueid's support may be completely cut off.

TYPE-MOON Fes. Official Pamphlet 10th Anniversary Q & A Booklet