Here are some examples:
When mara asking the Blessed One to Parinibbana, he said that he will not become Parinibbana until his bhikkhus, bhikkhunis, upasakas, upasikas (The four clans) become rich in Dhamma. In this four clan samaneras are included as Bhikkhus.
‘na tāvāhaṃ, pāpima, parinibbāyissāmi, yāva me bhikkhū na sāvakā bhavissanti viyattā vinītā visāradā…
‘na tāvāhaṃ, pāpima, parinibbāyissāmi, yāva me bhikkhuniyo na sāvikā bhavissanti viyattā vinītā visāradā
‘na tāvāhaṃ, pāpima, parinibbāyissāmi, yāva me upāsakā na sāvakā bhavissanti viyattā vinītā visāradā
‘na tāvāhaṃ, pāpima, parinibbāyissāmi, yāva me upāsikā na sāvikā bhavissanti viyattā vinītā visāradā SuttaCentral
In the categorization of the four clans, a samanera is a Bhikkhu.
(Do you think he is a upasaka? )
Again in the Etadagga Pali the Buddha nominates best disciples of the four clans. Here Ven. Cullapanthaka, Revat and Rahula were samaneras.
“Etadaggaṃ, bhikkhave, mama sāvakānaṃ bhikkhūnaṃ
manomayaṃ kāyaṃ abhinimminantānaṃ yadidaṃ cūḷapanthako.
… Cetovivaṭṭakusalānaṃ yadidaṃ cūḷapanthako.
… Āraññakānaṃ yadidaṃ revato khadiravaniyo.
… Sikkhākāmānaṃ yadidaṃ rāhulo SuttaCentral
If a best disciple monk cannot represent the Bhikkhu sangha, then what will they represent?
Generally samaneras are considered (in all the Buddhist coutries) a part of Bhikkhu sangha to the laity, though they are not allowed to participate in formal vinaya karmas. (as taught, as heard and as practiced by many)
Actully samanerahood is not a permanent rank but a transit to become a Bhikkhu. He is considered the son of the Bhikkhu.
Again in the following incident in Vinaya implies that samaneras are part of Bhikkhu sangha. (in many peoples’ opinion including me)
“Yo pana bhikkhu anupasampannena sahaseyyaṃ kappeyya pācittiyan”ti.
Evañcidaṃ bhagavatā bhikkhūnaṃ sikkhāpadaṃ paññattaṃ hoti.
Atha kho bhagavā āḷaviyaṃ yathābhirantaṃ viharitvā yena kosambī tena cārikaṃ pakkāmi. Anupubbena cārikaṃ caramāno yena kosambī tadavasari. Tatra sudaṃ bhagavā kosambiyaṃ viharati badarikārāme.
Bhikkhū āyasmantaṃ rāhulaṃ etadavocuṃ—“bhagavatā, āvuso rāhula, sikkhāpadaṃ paññattaṃ—‘na anupasampannena sahaseyyā kappetabbā’ti. Seyyaṃ, āvuso rāhula, jānāhī”ti. Atha kho āyasmā rāhulo seyyaṃ alabhamāno vaccakuṭiyā seyyaṃ kappesi.
Atha kho bhagavā rattiyā paccūsasamayaṃ paccuṭṭhāya yena vaccakuṭi tenupasaṅkami; upasaṅkamitvā ukkāsi. Āyasmāpi rāhulo ukkāsi.
“Ko etthā”ti?
“Ahaṃ, bhagavā, rāhulo”ti.
“Kissa tvaṃ, rāhula, idha nisinnosī”ti?
Atha kho āyasmā rāhulo bhagavato etamatthaṃ ārocesi. Atha kho bhagavā etasmiṃ nidāne etasmiṃ pakaraṇe dhammiṃ kathaṃ katvā bhikkhū āmantesi—“anujānāmi, bhikkhave, anupasampannena dirattatirattaṃ sahaseyyaṃ kappetuṃ.
And Bhikkhus give their robes and bowls, food, accomodation, medicine to samaneras which is prohibited to give to lay people. This also implies.
Otherwise even Arahant samaneras like Ven. Rahula will not receive any of four requisites.
And practically/conventionally when lay people invite a certain number of Bhikkhu sangha for an alms offering in a house, that number is filled with all Bhikkhus or all samaneras or both.