Trying to grow a nested dictionary by adding more key:value pairs

I am facing some trouble with trying to add more key:value pairs to a dictionary object that is itself nested within another dictionary object. Also, the usual way of doing dict[key] = value to assign additional key:value pairs to the dictionary is not suitable for my case here (I'll explain why later below), and thus this makes my objective a lot more challenging to achieve.

I'll illustrate what I'm trying to achieve with some statements from my source code.

First, I have a dictionary object that contains nesting:

environment = { 'v' : 
                  {
                   'SDC_PERIOD':'{period}s'.format(period = self.period),
                   'FAMILY':'{legup_family}s'.format(legup_family = self.legup_family),
                   'DEVICE_FAMILY':'"{fpga_family}s"'.format(fpga_family = self.fpga_family)
                   }
              }

and then following this line, I will do an if test that, if passed, will require me to add this other dictionary:

environment_add = { 'v' : {'LM_LICENSE_FILE' : '1800@adsc-linux'} , 
                    'l' : 'quartus_full' }

to ultimately form this complete dictionary:

environment = { 'v' : 
                  {
                   'SDC_PERIOD':'{period}s'.format(period = self.period),
                   'FAMILY':'{legup_family}s'.format(legup_family = self.legup_family),
                   'DEVICE_FAMILY':'"{fpga_family}s"'.format(fpga_family = self.fpga_family),
                   'LM_LICENSE_FILE' : '1800@adsc-linux'
                   } ,
                'l' : 'quartus_full'
              }

As you can see, if I were to try and assign a new key:value pair using the dict[key] = value syntax, it would not work for me because it would end up either creating an new key:value pair for me, or overwrite the existing dictionary object and the key:value pairs that are nested under the 'v' key.

So far, in order to accomplish the creation of the dictionary, I've been using the following:

environment = """{ v: {'SDC_PERIOD':'%(period)s','FAMILY':'%(legup_family)s','DEVICE_FAMILY':'"%(fpga_family)s"'}}""" % self
if self.require_license:  # this is the if statement test that I was referring to earlier
  environment = environment.replace('}', '')
  environment += """ ,'LM_LICENSE_FILE':'1800@adsc-linux'}, 'l': 'quartus_full'}"""

and then obtaining the dictionary object later with:

import ast
env_dict = ast.literal_eval(environment)

which gives effectively converts the environment string into a dictionary object stored under a new variable name of env_dict.

My teammates think that this is much too overkill, especially since the environment or env_dict object will be parsed in 2 separate modules later on. In the first module, the key-value pairs will be broken up and reconstructed to form strings that look like '-v SDC_PERIOD=2500s, LM_LICENSE_FILE=1800@adsc-linux' , while in the second module, the dictionary nested under the 'v' key (of the environment/env_dict dictionary object) will be extracted out and directly fed as an argument to a function that accepts a mapping object.

So as you can see, there is quite a lot of precise parsing required to do the job, and although my method fulfills the objective, it is not accepted by my team and they think that there must be a better way to do this directly from environment being a dictionary object and not a string object.

Thank you very much for studying my detailed post, and I will greatly appreciate any help or suggestions to move forward on this!