Is skydiving in IMC (through clouds) legal and safe? (1) What are the legal considerations for skydiving into clouds? I see many skydivers did fall into and out clouds in online videos. However, the clouds are mostly scattered or thin-layered. How about in widespread hard-IMC, say OVC 008? 

(2) What about maintaining the actual safety? How does a skydiver maintain attitude and stable position in IMC and not disoriented? and separation from other traffic?

EDIT: The legal consideration of my context is within US, but open to legal regulations worldwide.
It is not legal to conduct skydiving into clouds, atleast in US. From 14 CFR §105.17   Flight visibility and clearance from cloud requirements:

No person may conduct a parachute operation, and no pilot in command of an aircraft may allow a parachute operation to be conducted from that aircraft—
(a) Into or through a cloud, or
(b) When the flight visibility or the distance from any cloud is less than that prescribed in the following table:



Is it safe? Probably. The chances of mid-air collision are pretty small, but they can happen as is does with aircraft. Midair collisions between skydivers and between aircraft and skydivers are rare, but not unheard of. There has also been reports of near misses between aircraft and skydivers through clouds. So, its better to be safe.