You can find details of how and why in this document.
https://engage.gov.bc.ca/app/upload...d-Recommendations-of-the-Attorney-General.pdf
All of the details on most things about this referendum can be found here as they should.
https://elections.bc.ca/referendum
For those not wanting to dig through all this I'll just post a quote from the PDF.
Matters for Post-Referendum Decision -page 59
The voting systems recommended for inclusion on the referendum ballot are described in sufficient detail in this report for voters to understand how they would operate if adopted. However, there are a number of design and implementation details that should be left to post-referendum work. Although they are largely technical, these design details can have a significant effect on how a voting system works in practice, and should be decided by a transparent multiparty process. The number and complexity of those details depends upon the specific voting system, and the appendices describing the proposed PR voting systems also include a list of design details that would require decision post-referendum. Whether there should be any increase in the overall number of MLAs in the province is one example. Another is the issue under MMP (should it be adopted) respecting the design of the ballot for the List PR seats. Lists may be “closed”, “open” or “flexible”. For closed lists, voters endorse a party and its candidates as listed in the order put forward by that party. For open lists, voters may choose the candidates they prefer from amongst the candidates put forward by a party, or there may also be an option to endorse the party’s list as presented. For flexible lists, voters may choose individual candidates they prefer or they may vote to endorse the party’s list. While the feedback from the public engagement indicated more support for either “open” or “flexible” lists because they provide voters with more choice, the engagement also indicated support for simple ballots, which a “closed” list would provide. This is an issue that would benefit from further debate and discussion.
A number of respondents to the public engagement suggested that if the result of the referendum is in favour of adopting a proportional representation system, it is important that the details respecting that system be designed and implemented in a manner that is fair and transparent. However, as noted above, a lengthy post-referendum process involving an independent advisory body of experts as well as a cross-section of citizens to decide upon all design details creates a risk that the statutory deadline for implementing a new voting system would not be met. The best method for providing transparent public input on design and implementation while ensuring a reasonable timeframe for completion would be an all-party committee of the Legislative Assembly. The committee should receive input from independent experts, election administrators and the public on the remaining design details of the voting system to be adopted and issue a report with recommendations. None of the political parties represented in the Legislative Assembly under its current composition would have a majority on such a committee, and therefore the committee’s recommendations would require thoughtful compromise among all the parties.
Beyond the design decisions for the committee and the Legislature, if any of the proposed PR systems are adopted, an independent Electoral Boundaries Commission would be required to recommend new electoral boundaries for the province. The scope of the commission’s task would vary depending upon the voting system and the degree of direction given it by the Legislature: for example, whether it is required to propose a specific number of electoral districts/MLAs for the province or whether it is given a numerical range to work within, and whether it would be required to delineate specific regions of the province
