Sometimes when writing, we need to express the idea that something has happened during a period of time that is not explicitly mentioned. When this occurs, we might need to use synonyms for the phrase "in the intervening time". One option is to use "in the meantime", which conveys a similar idea but is less formal-sounding. Alternatively, we could use "in the interim", which implies that the time period is more temporary than "in the intervening time". A more casual synonym would be "in the meanwhile", which is still effective at expressing the same idea. Ultimately, the choice of synonym will depend on the tone and formality of your writing.