The English translations of Scriptures do not convey with consistency the original words. The greek words thelēma (desire – eg. Luke 10:24) and boulē (counsel – eg. Acts 2:23) are both translated as the same English word, “will” (Luke 22:42). To avoid confusion and be precise, let us use the greek words or for simplicity, refer particularly to either the desire or the counsel of God.
Now, Eph 1:11 posits that there is a sequence of God’s acts – He works. According to the counsel – Of His desire. Intuitively, this is how we act too – we begin with a desire, say to eat ice cream. And at the same time, we may have the desire to perform well at a singing contest the same day. Next, I counsel between my available desires, weighing the pros and cons – and eventually, the desire with the highest priority ‘score’ wins. I finally work out that counselled desire to fulfillment, considering circumstances yield.
Similarly, God sovereignly desires anything consistent with His perfect nature – then counsels to have it fulfilled – and finally works it out by His power. God is not limited by anything – what He desires, He will have fulfilled. His desires are never thwarted. Consequently, God does not have multiple options of desires at the same level over the same thing. God does not debate within Himself over His own desires whether or not to have something fulfilled – He simply has one perfect desire and He accomplishes it and then moves on to His next desire.
Of course, once having made His counsel over His one perfect main desire, God’s counsel could entail splitting His current desire into sub-tasks or a series of sub-desires that need to be similarly counselled and worked upon. These subsequent desires still fall under the hierarchy of the preceding main desire and counsel, though they may again give rise to further such chains. A main level, hierarchical root desire can be termed purpose.