Is praying for a walk-in replacement a preferable opportunity to committing suicide if this can be arranged through the divine realm?

This can be so because it provides an orderly transition and hand-off that serves another karmic purpose for another individual, and can be a mitigating factor in the decision to surrender the life and seek an escape. As you know, suicide is never an ideal circumstance. It is acceptable under conditions of extreme duress and intolerable suffering and is the lesser of evils by far than to continue to incur horrendous pain and suffering that will worsen damage. This is especially the case when all avenues for obtaining relief have been exhausted and should never be the first thought or the first strategy chosen, but many, many people reach this extreme having exhausted all avenues available to them to obtain relief, or believe they have. We do not judge such individuals. They will be faced with the karmic consequences of their choices, but sometimes the ability to start fresh in a new life will give them more of a fighting chance to surmount a large backlog of karmic negativity they could not otherwise handle in the current life and may be more successful in the next round. It may lengthen the struggle but sometimes it can be done in a less devastating way and that is certainly preferable to the individual involved. This is a relatively rare eventuality and the main stumbling block is not only the lack of awareness this can be an option, and so cannot be requested by most people, it is also complex to arrange because of the need for acceptance of that individual soul extension in physical form. With the karma linked to the body being approved as a blending with another soul who wants to come in, this creates complications for the newcomer and is often taking them away from their soul group, so in some ways it is a sacrifice and must also be approved by others involved in the family unit, so not all will agree—that is the major obstacle for this becoming a widespread practice.