Merge Java Web Applications

I am new to java development, I am supposed to merge two java applicati开发者_开发问答ons, first one is OpenCMS and second one is an old core java (Servlets and JSPs) based application (also it has many other technologies like struts, JSF and Hibernate etc.) I need some basic idea regarding this.

Figure out the functionality missing in one, and re-implement it. It is far easier to keep a consistent core set of practices on how it's done in one than to make a beast which marches to the beat of two out-of-sync drummers.