Pairs are kept together over winter should, hopefully, come spring, the combination of familiarity and the fact that they have shared the same perch for months, will have created a bond.
If the birds have bonded, the signs will be obvious come April, when the finch cocks will be seen feeding the canary hens as their begging cries become more persistent as the breeding season approaches.
This is more evident with the Siskin cocks, which seem to be more tolerant of our presence in the birdroom.
Goldfinches, however, seem shyer, and a bond can often only be confirmed by peering through the corner of a window or the gap of a half-opened door.

When the hens are ready to go to nest, they will be seen carrying mouthful’s of whatever nesting material is available to them: wood shavings, feathers or newspaper, when this is witnessed the nest pans can be introduced along with proper nesting material.

This is an important stage for me, at this point; I treat my Sickins and goldfinches differently.
I am sure that other breeders have their own way, but this method works for me, with 23 miniature mules bred from 4 hens in 2004.
When the nest is complete, I split the Siskin cock and canary hen by way of a wire divide every evening. I reintroduce him in the morning, after I have replaced any eggs laid with dummy ones.
This is done until the clutch is complete.

The Siskin cock is then kept apart as before, because Sickins, above all other British finches, have a tendency to eat the eggs and cannot be trusted!
However, more often than not the Siskin can be relied upon to fertilize the eggs in the first round.

All going well, the cock Siskin can be reintroduced once the young mules have hatched, where he will happily carry out his parental duties (help with feeding the young) even after the youngsters have left the nest.

I use different tactics in trying to breed Goldfinch mules at this stage.
Instead of leaving the finch cock with the canary hen, I shut him off, again by use of a wire mesh divide, and I run a canary cock with the hen until her clutch is complete.
I do this firstly, because I can obtain young canaries for the following year, and second, as the Goldfinch sometimes do not come into full breeding condition until May: eggs laid before this are usually clear.

When the young canaries hatch and not before, because Goldfinches, like Sickins are partial to eggs the finch can be returned to the hen.
One of the benefits of my way with Goldfinches is that, when the hen is ready to go to nest for her second round, the canary cock to which she was previously mated can be brought into view; I do this by way of an all-wire cage suspended from the ceiling.
With any luck, she will respond to his singing, and the finch will successfully mate with her, resulting in a clutch of fertile eggs.
This should be done four or five times during the course of the day or evening, for no more than ten minutes at a time. It is also important that the fancier leaves the bird- room at this point as the Goldfinch- and who can blame him? - likes his privacy.

In producing show quality miniature mules, my best results have come from pairing yellow Siskin cocks to yellow green Fife hens, or yellow Goldfinch cocks to yellow half Fife, half Irish fancy hens.
Many people advocate the use of colored (red factor) canaries, in my opinion, whilst these tend to produce quite colorful miniatures, when the Goldfinch is used; the offspring tend to be on the large size and do not quite catch the judge's eye.
Maybe if the smallest intensive red hens were used instead of today's exhibition reds, which, to me, seem to have grown larger, some nice eye-catchers would grace the show bench.