Plugin Attribute Access

We have several plugins. Certain plugins needs to act based on other plugins attributes value in appendTransaction. An example scenario - I need to deal with - when entering a new line plugin1 adds some node attributes, plugin2 copies this, but checks if plugin1’s certain attribute values’ presence and need to update the value of attribute accordingly. Right now works fine with hardcoded attribute name accessor. Schema for these node attributes are managed the corresponding plugins. Being a plugin, believe it is not good to access other custom plugin attribute in the plugin. So checking here what is the best solution to handle this ie to avoid inter plugin dependency? Thanks!