Question: how to connect two eyepieces together with the x3 Barlow lens

I have 10mm,25mm, and x3 Barlow. Is there any way to connect them together to archive the maximum magnification of 105mm?

Answer: 
I'm not an expert, but I looked into this recently when toying with the idea of a scale model of the observable universe. To the best of my understanding, the following is approximately correct.

TLDR: The expansion happens on the very large scale of the universe. At the scale of the observable universe the Andromeda galaxy is a next-door neighbour, and at the local scale gravity is strong enough to override any effect of expansion.

The Milky Way is 100,000 light years across, 2.5 million light years brings us to the Andromeda galaxy. 

Galaxies cluster in galaxy groups, and 10 million light years span about 50 galaxies and brings us to the edge of what's called the Local Group. 

Galaxy groups cluster into superclusters. We're part of the [Laniakea Supercluster](https://www.space.com/27016-galaxy-supercluster-laniakea-milky-way-home.html), which spans about 100,000 galaxies and 500 million light years. 

For any appreciable expansion (redshift 0.1) you need at least a billion light years. It's something that happens in the voids between superclusters, and doesn't become really pronounced until you're halfway across the observable universe (redshift 1, 7-8 billion light years as measured in light travel time).

For the "raisins in a loaf" analogy, I think it's not too wrong if you think of the raisins as superclusters rather than individual galaxies. Note that although the dough expands in a baking loaf, individual raisins do not, because there are other forces at work that hold them together.
In general, space in the Universe is expanding. However, this expansion can be locally retarded by high enough densities of mass-energy. On very large scales, the mean density is low enough that you can treat the whole universe as expanding. But if you look on smaller scales, you can find underdense regions (voids) where the expansion is actually *faster* than average, and overdense regions where the expansion is slower or has even ceased. Inside of clusters and galaxy groups (and of course inside galaxies themselves), the density is high enough that space is no longer expanding, and so it's perfectly possible for galaxies to move through local space towards each other and collide.

So in your raisin-loaf model, the trick is that regions right around each raisin -- and in local regions containing several raisins close to each other -- *aren't* expanding.

Note that j-g-faustus' argument is somewhat incorrect: if expansion only occurs in voids between superclusters, then Edwin Hubble would never have found it by looking at galaxies within the nearest 30 million light years. Space inside individual clusters and groups is not expanding, but space within superclusters *is* (just not as fast as space within voids).