Is it permissible to adopt one opinion regarding making up missed prayers, then switch to another opinion due to hardship, knowing that some fluid issues from me after purification (istinja') and during prayer?

The disagreement regarding the obligation to make up intentionally missed prayers is well-known, and the preponderant opinion is that they must be made up. As for the issue of water discharge after istinja’ (washing after using the toilet) and during prayer:

- If the water is from vaginal moisture, it is pure, but it nullifies wudu’ (ablution). However, if it is continuous, you perform wudu’ once after the time for prayer begins and pray the obligatory and supererogatory prayers with that wudu’. Your wudu’ is not nullified as long as the prayer time remains.

- If the water is drops of urine, the ruling is the same. You should place something after istinja’ to prevent the discharge from spreading, perform wudu’ after the time for prayer begins, and the wudu’ will not be nullified by the discharge of drops.

There is no harm in adopting the easier opinion here to alleviate hardship.