How to manage multiple release versions in development at the same time for same product?

[Bar T]

We want to release a version "1.1" in 2 months.

Feature X is huge (architectural change with dependancies). Feature Y and Z are manageable.

Team is working on Feature X now, but know it won't be feature complete for awhile. 

Is it better to:

A) Flag tickets as 1.1 fix version and drop them in the sprints? or

B) Work off two fix versions in parallel?

Goal is to be able to report what features will make the 1.1 release but also show that work is being done on other long term feature.

[Troy Spetz]

We use JIRA 7.10 server version.

If you are committing code for Feature X in the same code base as for the release which will contain the 'manageable' Features Y and Z, then the work for Features X/Y/Z should be against the same FixVersion.

Even if you are not going to announce Feature X (when you announce Feature Y and Z), the software contains (hidden or alpha-/beta-feature) Feature X's work done so far as well.