For example:
I want to add a reference from a book, page 11 - no problem. But, later I want to add a reference from the same book, but with different page.
So, I want to use the same resources, and change only page.
It depends on how you use the built-in bibliography. Writer imposes no constraint on use the “Pages” field. Generally, this field displays the count of pages of the published book, not the location of the reference.
Either you consider this field to be part of the reference itself and you fill it with the page number where you find your quotation. This means then that you have two different logical references for two different pages and the consistent consequence is you must have two bibliography entries (with the annoyance that most of the records are identical and must be hand copied with the risk of errors).
Or the bibliography only lists the books you have read or recommend to your readers and the page location is an “external” additional data you enter aside the bibliography reference in your text.
You may have a look at what Zotero or Mendeley plug-ins do though I usually don’t recommend them because IMHO (at least for what I do regarding automated – and highly consistent – formatting) they don’t integrate smoothly with Writer, in particular messing up the style feature with direct formatting.