Question when upgrade JDK

We are following " Using JDK 7.0 Latest Update with Oracle E-Business Suite Release 12.0 and 12.1 (Doc ID 1467892.1) " to upgrade 10.1.3 and 10.1.2 HOME JDK

apart from having JDK under ORACLE_HOME (10.1.3 + 10.1.2), we could see JDK under below directories

./apps_st/comn/java/classes/oracle/apps/ja/cnao/jdk
./apps_st/comn/util/jdk
./tech_st/10.1.2/inventory/filemap/jdk
./tech_st/10.1.3/jdk
./tech_st/10.1.3/inventory/filemap/jdk

Just wanted to know,

1. Can we upgrade above mentioned  JDK's apart from JDK under ORACLE_HOME (10.1.3 + 10.1.2) ?

If Yes,
2. Any supporting document related to this?
3. Will there be any major impact if we upgrade these JDK's to the same version as of JDK under ORACLE_HOME (10.1.3 + 10.1.2)