Thanks for your questions. Canon 603 was meant for solitary hermits, that is hermits who are professed in the hands of the local ordinary and live on their own according to a Rule they write themselves and which is approved by the local ordinary. There are provisions in canon law for semi-eremitical communities but what was missing was a way for solitary hermits to be recognized in universal law and consecrated as a unique form of religious life. Canon 603 filled that bill. Because it was meant for individuals and not as a short cut to creating a semi-eremitical community, care has been taken by some Bishops' conferences and commentators on the canon, as well as by individual dioceses like my own to make sure the canon is used appropriately and wisely to protect a really rare and significant vocation.
The reason the situation I outlined in the earlier posts made me wonder was because a particular diocese had established what began as a laura of hermits as a canonical community. This makes it appear that if one wants to become a hermit in this diocese one needs to do so through this community, via its formation program, according to its Rule, under the supervision of its superior, with all of the limitations and specifications required for life in this community. I wonder, therefore, what happens to someone who wishes to be professed and consecrated according to canon 603 without doing so under the aegis of this community. Canon 603 allows for this, in fact, once again, it is the very reason the canon was created. I don't know if the diocese in question has solitary c 603 hermits, however.
Similarly, I wonder what happens to a hermit professed as part of this community who desires to go apart and live as a solitary hermit as so many of us are doing now; if the community is still using canon 603 to profess members then it should be possible, but in that case a lot of particulars need to be established. The hermit will need to find housing, establish herself as part of a parish, make sure she is capable of supporting herself, take care of insurance needs, establish a relationship with a spiritual director, and anything else a solitary hermit needs for living this life on her own. If such a hermit was not part of the original laura, they might not have discerned a solitary eremitical vocation at all and may be entirely unprepared to live such a vocation.
Like questions arise when a diocesan hermit wishes to relocate to the diocese in question and does not wish to become a member of this community. Would she be allowed to live her vocation in this diocese? Would the bishop accept her vows without forcing her to become part of this community? And then too, there are the questions raised should the community fail. These are the same questions raised above but instead of there being just one hermit needing to find housing, etc, you might have several. Finally, what happens when a perpetually professed hermit (or several of them) begin to understand this is not a laura (as it began or was billed as) but a community. Can they demand changes? Can they leave and form their own laura with the diocese's assistance and support or will the diocese insist on dispensing their vows? The answers depend on several factors but especially whether the diocese is still using c 603 to profess members.
Limiting a laura to three hermits does away with the group's tendency to grow (or morph) into a community with greater centralization and more structured governance, finances, single Rule, uniform dress, more need for building projects and maintenance (chapel, refectory, library etc). Three or fewer hermits are more apt to remain financially independent (some expenses will need to be shared but this will be far more limited without a common purse), be able to live according to their own Rule and horarium, and undertake the work they need to do to support themselves with a minimum of bother to the others in the colony. (And while this may sound selfish, in a laura each hermit is responsible for providing for her own medical needs and caregivers; the others in the laura are not responsible in any ongoing way for providing such. To be required to do this in a laura could well mean being required to live contrary to one's own Rule of life.) Finally, the temptation to seek out new members or shore up numbers to allow for the community's continuation over time does not occur when the laura can only consist of a very small number of solitary hermits who know they may need to live their vocations without the support of other solitary hermits at any time.
Let me just add that while I live as a solitary hermit I definitely appreciate the need for mutual support in this vocation; a laura could serve those needs and still leave one free to respond to the Holy Spirit in the ways one's own call requires. When a laura becomes a canonical community of diocesan right, then members are no longer solitary hermits and should not use canon 603 for professions. Instead, they should be using the same canons every other religious institute uses for governance, formation, admission to profession, the content of the vows (especially of religious poverty), etc. Once a laura is transformed from a colony of c 603 hermits into a canonical semi-eremitical community we are talking about a shift to a different vocation. Both vocations are eremitical of course, and the central elements of eremitical life will be found in both, but their differences are also significant. Dioceses must be cognizant of this and honor the solitary eremitical vocation canon 603 sought and was promulgated to provide for.