Splitting a document to show it in several RadRichTextBox instances is not a scenario supported out of the box and we have no similar example. While it is possible to create several RadDocuments from a single one, losing some of the formatting is expected. For instance, a list determines its number/bullet based on the previous paragraphs in the document. If you split a list in half it is only natural that its numbering would be restarted.
Could you please share more details on your end scenario? For example, why do you want to split a document? Is showing several controls containing rich text necessary in your scenario and why? What type of documents are you using? Are you planning to export the document to any of the supported formats? Maybe we will be able to suggest an alternative for you that does not require the creation of several RadRichTextBox instances.
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