You don't want to inbreed any fish (including guppies) if you can help it.
Moscow guppies are generally unrelated to lyretail guppies so crossing them together shouldn't be an issue. If you use 1 male lyretail to breed with the female Moscows, then you can use the second male to breed with any female babies that are produced. If you have a number of unrelated males, then you can keep using unrelated males to breed with the young females from each batch.
Before you breed the females with the males, you should leave the females for 6 months or so to use up any sperm packets they carry. Common livebearers like guppies, mollies, swordtails and platies can carry 6 or more sperm packets from breeding with different males. The females can choose when they want to use a sperm packet to fertilise the eggs. The remaining sperm packets remain inside the female and she can use them any time conditions are good. Good conditions means good water quality, lots of food, a nice warm temperature, and no predators. Because the females carry the developing eggs for about 4 weeks, females can give birth about once a month for 6 months or more (depending on how many sperm packets they have), without any males being present. Once they run out of sperm packets, that's when you breed the females with new males.
If you get young females from your babies, keep them away from all males for the first 12 months. This will allow them to grow to maturity and develop properly, and they will have less issues when they become gravid (pregnant) and when they give birth. If you don't want to wait 12 months for the females to become fully mature before breeding, at least let them get to 6 months of age before breeding them. The females need to be physically strong enough to withstand the rigors of childbirth (guppy birth).
PONDS WITHOUT FILTERS
Most freshwater fish can live in ponds without aeration or filtration. However, they need lots of live plants and a large water volume otherwise there is a chance they will die from poor water quality or sudden changes in temperature. Some people have fish in small (50-100 litre/ 12-25 gallon) ponds and they do alright. But the smaller ponds will have much wider temperature fluctuations and you won't be able to keep as many fish in it. The smallest outdoor pond you want is around 4 feet in diameter x 2 feet high, and bigger is better. I like above ground aquaculture ponds that are 8-10 foot diameter x 4 feet high. However, you need space for this size pond.
Aeration from an air pump, water pump or water feature is recommended in any pond even if it doesn't have a filter. The aeration helps mix the water so it is a more even temperature throughout, and helps reduce low oxygen levels in hot weather, which can kill fish.
HOW MANY BABIES
Female guppies can produce between 10 & 100+ young per batch and can produce a batch of fry every month. Bigger older females will usually have more babies but they might only give birth once every 2 months. Smaller younger females usually have smaller batches and give birth about once a month under good conditions.
Guppies don't normally eat their young if the adults are well fed and there are plenty of plants in the tank. A lot of people simply leave the babies with the mothers and remove nay baby males as soon as they can be identified. But if you have 10 females giving birth each month, you can end up with lots of babies.
CULTURING FISH FOODS
The following link has information about breeding fish in general and culturing food for the babies. It might interest you.
Livebearers like guppies, mollies, swordtails & platies are regularly infected with gill flukes and intestinal worms. If you want to breed them, deworm the fish and treat them for gill flukes before you do anything else.
Intestinal worms like tapeworm and threadworms cause the fish to lose weight, continue eating and swimming normally, and do a stringy white poop. They don't always have these symptoms but most do. Fish can do this for months and not be too badly affected. In some cases, fish with a bad worm infestation will actually gain weight and get fat and look like a pregnant guppy. This is due to the huge number of worms inside the fish.
You can use Praziquantel to treat tapeworm and gill flukes. And use Levamisole to treat thread/ round worms. If you can't find these medications, look for Flubendazole, which treats both lots of worms.
In the UK look for:
eSHa gdex contains praziquantel that treats tapeworm and gill flukes.
eSHa-ndx contains levamisole and treats thread/ round worms.
NT Labs Anti-fluke and Wormer contains flubendazole.
Kusuri wormer plus (contains flubendazole) - sold mainly for discus, comes as a powder which is quite hard to dose in smaller tanks
Sera nematol (contains emamectin)
Remove carbon from filters before treatment and increase aeration/ surface turbulence to maximise oxygen levels in the water.
You treat the fish once a week for 4 weeks. The first treatment will kill any worms in the fish. The second, third and forth treatments kill any baby worms that hatch from eggs inside the fish's digestive tract.
Treat every fish tank in the house at the same time to prevent cross contamination.
You do a 75% water change and complete gravel clean 24-48 hours after treatment. Clean the filter 24 hours after treatment too.
Do not use the 2 medications together. If you want to treat both medications in a short space of time, use Praziquantel on day one. Do a 75% water change and gravel clean the substrate on day 2 & 3. Treat the tank with Levamisole on day 4 and do a 75% water change and gravel clean on day 5, 6 & 7 and then start with Praziquantel again on day 8.
The water changes will remove most of the medication so you don't overdose the fish the next time you treat them. The gravel cleaning will suck out any worms and eggs that have been expelled by the fish. Repeating the treatment for 3-4 doses at weekly intervals will kill any worms that hatch from eggs. At the end of the treatment you will have healthier fish.