Passion Flowers & Morning Glory (Ipomoea)

My experience with Passiflora edulis is that it needs frequent watering. Ours grows indoors in a shady conservatory but fruits well. Earlier in the year I neglected the watering and found a lot of the small fruit fell off. This got worse initially after I watered heavily.
I don't think they need much feeding as mine is growing in a sort of 'trough' which was filled with very poor earth, though they can root down into the clay beneath. Apart from putting down some slow release fertiliser pellets, that's all they get, and they generally are growing rampantly.
I know Caerulea isn't quite the same, but I'd say water is more important than feeding.
Morning Glory is just a weakly little annual and couldn't possibly do harm to a strong perennial climber like Passiflora Caerulea.

I wonder if feeding the outdoor one is actually contraindicated. My neighbour had one which completely took over her garden, and actually came through my window during the night! She never fed it at all & I used to hack loads of it off when it came over the wall.We have terrible sandy soil but the passion flower loved it. Be careful what you wish for!

The morning glory definitely won't be strangling the passion flower, more likely to be the other way round if at all. You don't say whether these plants are in a pot or the ground, but I just wanted to say that, whilst Fish Blood and Bone is very good in the soil, as a feed for plants, its pretty hopeless - it feeds the organisms in the soil and eventually, after some months at least, the plant will get the benefit, but only after some time. For an instant hit, you need to give it something else, like Growmore, or water on Phostrogen, or Miracle Gro general purpose.