Short Answer: You CANNOT.
The closest that you can get is that ...
You could "Enable Relationship Viewing"; but, that is ONLY on a 'one by one' basis.
ALL "Registered" Users/Patrons of 'FamilySearch' can 'see' ALL the "Deceased" individuals/persons that are in "Family Tree" of "FamilySearch' - just NOT an "Living" individuals/persons.
As an aside ...
We do not have our OWN "Tree" in "Family Tree" of 'FamilySearch'.
We ONLY have "Branches" (ie. 'Ancestral' lines), that are interconnected, in this SINGLE "One" World "Tree", for all of us, that is "Family Tree" of 'FamilySearch'.
"Family Tree" of 'FamilySearch" is NOT like Other "Websites" (eg. "Ancestry_com"); and/or, 'standalone' personal programmes (eg. "Ancestral Quest"); or, the like.
We DO NOT have "Private"/"Personal" 'Trees' in "Family Tree" of 'FamilySearch' like Other "Websites"; and/or, 'standalone' personal programmes.
We do not even, own; or, manage; and, are NOT even responsible for, the "Deceased" individuals/persons in "Family Tree" of "FamilySearch'.
"Family Tree" of 'FamilySearch' is built on a "Open Edit" Platform - hence, why any registered User/Patron can "Edit" (ie. Add, Delete; and/or, Change) ANY "Deceased" individual/person in "Family Tree" of 'FamilySearch'.
You can ONLY see "Deceased" individual/person in "Family Tree" of 'FamilySearch'; except, with this 'rider', that you can ALSO only see "Living" individual/person in "Family Tree" of 'FamilySearch' that YOU created; as, they reside in your "Private Spaces".
No other User/Patron can see ANY "Living" individuals/persons that were created by another User/Patron; as, they ONLY reside in the "Private Spaces" of the User/Patron who created them.
We CANNOT even see the ACTUAL Record in "Family Tree" of 'FamilySearch' of our IMMEDIATE Family (eg. Spouse; Children; Parents; Siblings; ETC; Etc; etc) if they are "Living"; and, they have their own 'FamilySearch' Account.
Of course, you can create your "Living" Family members; and, record them in "Family Tree" of 'FamilySearch'; but, they will ONLY be seen by you:
- You cannot "Share" them with any other User/Patron.
- You cannot "Merge"/'Combine" them with any other "Living" individual/person residing in the "Private Spaces" of another User//Patron.
There is CURRENTLY no mechanism in "Family Tree" of 'FamilySearch' for Users/Patrons, to "Share"; or, "give permission" to "Share", the "Living" individuals/persons in their own "Private Spaces" with/between other/another User/Patron.
There are a myriad of "Privacy" Laws within the many various Countries and Unions throughout the World - it is a nightmare to negotiate.
"Family Tree" of 'FamilySearch' is used in many Countries and Unions throughout the World; and, as such, must adhere to the myriad of "Privacy" Laws throughout the World.
Hence, "Privacy" is one of the reasons that we cannot "Share" the "Living" individuals/persons in our own "Private Spaces" - it is NOT the ONLY reason; but, certainly has a bearing on the matter.
Another factor is that such would have to be 'Coded'/'Programmed' into the Programme that is "Family Tree" of 'FamilySearch'.
'Yes', these "Living" individuals/person in "Family Tree" of 'FamilySearch' WILL, in fact, in many (most) cases will be "Duplicated" - unfortunately a necessary situation that currently cannot be avoided.
I know that there are "Duplicates" of the "Living" ME - at least, one for my Wife and each of our Children, not to mention my other ("Living") extended Family members.
Here are some "Knowledge Articles" in 'FamilySearch' in regard to "Private Spaces" and "Living" individuals/persons:
What is a private space in Family Tree?
Who can see my living relatives in Family Tree?
Here is a good place to start, with how things work in "Family Tree" of 'FamilySearch' (and, other programmes as well):
Introducing The Family History Guide
The Family History Guide
I hope this helps.
For the parts of your tree that are people that are deceased - we all already have access - this is a collaborative system where we all share a single database (except for living people which you have entered - that are kept private under your account)
see this info about how you can share info on your tree: