In reply to to_learn_uvm:
No you cannot cross from two covergroups, I believe that this has been a request for quite a while,
1800-2017 LRM Section 19.3 will give you enough information. you can also check here for examples. Keep in mind that not all simulators support all features.
The exact phrase of the LRM
"Cross coverage is allowed only between coverage points defined within the same coverage group. Coverage points defined in a coverage group other than the one enclosing the cross cannot participate in a cross.
Attempts to cross items from different coverage groups shall result in a compiler error."