1.
If you ~ something such as an agreement, discussion, or relationship, you become involved in it. You can also say that two people ~ something. (FORMAL)
I have not entered into any financial agreements with them...
The United States and Canada may ~ an agreement that would allow easier access to jobs across the border...
No correspondence will be entered into.
PHRASAL VERB: V P n with n, pl-n V n, be V-ed P (non-recip)
2.
If one thing enters into another, it is a factor in it. (FORMAL)
There were also other factors that entered into the orchestration.
PHRASAL VERB: V P n