I had to add a blank line to fix an error in /etc/openldap/adminmart.com.ldif, and I added for groups :

dn: dc=adminmart,dc=com
dc: adminmart
description: LDAP Admin
objectClass: dcObject
objectClass: organizationalUnit
ou: rootobject

dn: ou=People, dc=adminmart,dc=com
ou: People
description: Users of adminmart
objectClass: organizationalUnit

dn: ou=Group, dc=adminmart,dc=com
ou: Group
description: Groups of adminmart
objectClass: organizationalUnit

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I copied all of my groups that I wanted in ldap from /etc/groups to /etc/openldap/groups.txt and then ran:
/usr/share/openldap/migration/migrate_groups.pl /etc/openldap/groups.txt /etc/openldap/groups.ldif

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After I imported users, and groups, I used phpldapadmin to import shadow passwords. I opened /etc/shadow and copied the password field:
username:$1$0oDpBoKc$qw6grPT4jqgfqkc5Kzd/G.:_____:_:_____:_:::
as {crypt}$1$0oDpBoKc$qw6grPT4jqgfqkc5Kzd/G.
And selected clear in the drop down so it would not try to re-encrypt (mangle) the password.

There is likely a scripted solution for shadow passwords, but I only had about 15 users and it was faster to just do it.