Continue marks around the inline node

Consider a font family mark applied on a text now i want to insert a custom contentEditable=false inline node and after which i will write type what i want is the font-family mark should continue.

Also I want to only apply marks like font-family and font-size to be applied.

Using [...] to represent content in marks...

[This is is font Mark   ^] 
Cursor is at this position  ^, 
now i will insert a content editable false node here.

WhatI want to happen is that the content editable false node be inside the mark or have s seprate mark wrapper, such that node and cursor after it follows previous mark.

1. split mark nodes
[This is is font Mark ][(custom node)][  ^ ]
Cursor is already in mark node.

2. append in same mark

custom node
 [This is is font Mark (custom node)   ^]

How can I acchive this?

Possibly by having the command that inserts the node also set stored marks?