With multiple branches, many of which grow out from near the base, there are more chances to air-layer. I even wrote an article to explain a technique on how to air-layer on crowded branches in a pot.
Serpentine or Compound Layering
A propagation technique that can be performed on plants is called compound or serpentine layering. Traditionally, compound layering has been done on long branches on the ground (ground layering).
Essentially, it is just a series of simple layering. Here's an illustration of how compound layering works.
I've done a similar layering technique using cups on a Mandevilla. The Mandevilla had many branches but isn't planted on the ground but in a pot. So I had to find a way to "ground-layer" the branches which had varying lengths.
Compound air-layering works on the same principle. The only difference is you perform a series of air-layers. Here are the steps to air-layering or marcotting.
Recently, I've done compound air-layering on a Nong Nooch vine planted in a hanging basket. Here is the vine as shown below. The compound air-layering is done on several branches also.
Secret to Successful Compound Air-Layering
Rooting of the air-layer or marcot is the aim of air layering. I believe a crucial step to successful air-layering is the correct placement of the air-layers.
This would require careful planning and thinking ahead. Where to cut the air-layers will form part of the decision.
Notice the compound air-layers performed on a branch below.
There are two air-layers: one on top and the other at the bottom of the picture. The top air-layer is on one of three branches coming out from the branch where the bottom air-layer was made.
The cutting points for both air-layers are shown marked in blue in the photo above.
Cutting the Compound Air-Layers or Marcots
By cutting on the identified points, the air-layers have a much better chance of surviving. In the photo below, the pruning shears are positioned to cut at the correct point for the top air-layer.
You can see the top air-layering having its own foliage (leaves and stems). When the pruning shears cut, the bottom air-layer will be left with the remaining foliage (two stems). This "balances" the foliage for both the air-layers.
If the top air-layer is cut below or at the "not here!" label, then there will be no leaves and stems left for the bottom air-layer.
After cutting, you can see the bottom air-layering still getting two stems with leaves as shown below. This foliage helps jumpstart the growth of the new plant.
Shown here are the two cut air-layers with their network of healthy roots.